The measuring stick for a successful season varies for every MLB team.

Some clubs are in championship-or-bust mode, while others would be happy to simply reach the postseason. There are also teams building for the future that might judge their success based on how individual players develop. So let's pick out something for each of the 30 clubs to focus on this year. 

Here's one key number for every team that could define its 2024 season.

AMERICAN LEAGUE EAST

Blue Jays: Vladimir Guerrero Jr.’s home run total

The Blue Jays have made the postseason as a Wild Card in three of the past four years, but the team hasn’t won a division title since 2015 or a postseason game since ‘16. With Guerrero and Bo Bichette both eligible to test free agency after 2025, it may be now or never for Toronto to contend with its current core. The question is, which version of Vlad Jr. will show up in 2024? The one who finished second in the American League MVP race after producing 48 homers and a 1.002 OPS as a 22-year-old in 2021? Or the one who has combined for 58 homers and an .804 OPS over the past two seasons?

Orioles: Starting pitcher ERA

The Orioles have talked a lot about wanting to make a play for an impact starter, but to this point they haven’t added anyone to their rotation. That puts the spotlight on their returning arms to provide support for Baltimore’s impressive crop of young position players as the team looks to build upon a 101-win season. There's a lot of pressure in particular on 2023 breakout star Kyle Bradish and sophomore Grayson Rodriguez, who rebounded from a rough start to his rookie season but was hit hard by the Rangers in his lone playoff outing.

Rays: Taj Bradley’s ERA

The Rays typically find a way to field a competent pitching staff no matter who is on their roster, but that could prove to be more of a challenge this season if Bradley doesn’t step up. With Tyler Glasnow now with the Dodgers following a December trade and Shane McClanahan, Jeffrey Springs and Drew Rasmussen all sidelined while recovering from elbow surgery, Bradley is one of the pitchers Tampa Bay is counting on to provide effective length behind its No. 1 starter, Zach Eflin. Bradley, who was MLB Pipeline’s No. 18 overall prospect when he made his MLB debut last April, struck out 28% of the batters he faced as a rookie but also allowed a ton of hard contact while posting a 5.59 ERA over 104 2/3 innings.

Red Sox: Starts of 5-plus innings pitched

Boston swapped out Chris Sale for Lucas Giolito, but the team’s rotation otherwise looks a lot like it did at the start of the offseason, which surely isn’t what Red Sox fans expected. The team’s rotation not only struggled to prevent runs (4.68 ERA) but also failed to provide length in 2023, recording only 98 starts of at least five innings -- the fourth fewest in MLB. As a result, Boston’s bullpen was overworked and wore down in the second half. The Red Sox's postseason hopes may rest on its starting staff finding ways to improve in 2024, which means a bounceback season from Giolito, the continued development of Brayan Bello and Kutter Crawford and Nick Pivetta keeping up last year’s strong finish.

Yankees: Carlos Rodón’s WAR

The additions of Juan Soto, Alex Verdugo and Trent Grisham shored up two of the Yankees’ biggest issues from 2023 -- a lack of left-handed hitters and a dearth of outfield production by players not named Aaron Judge. However, the Bronx Bombers still have some major question marks in their rotation behind reigning AL Cy Young Award winner Gerrit Cole. The biggest of all? Rodón, who posted a 6.85 ERA with -0.9 WAR (per Baseball-Reference) over 14 starts in the first season of a six-year, $162 million deal with New York. The Yankees need Rodón healthy and pitching well, like he was when he produced 10.5 WAR across 2021-22.

AL CENTRAL

Guardians: Bo Naylor’s OPS+

With Shane Bieber and Triston McKenzie due back from injuries and Tanner Bibee, Gavin Williams and Logan Allen all coming off promising rookie seasons, the Guardians could potentially have one of the AL’s best rotations in 2024. However, their lineup may once again stand in the way of an AL Central title. Outfielder Estevan Florial and catcher Austin Hedges are the only notable additions Cleveland has made this offseason to an offense that ranked 27th in MLB in runs scored (662) last year. Getting a breakout year from the 23-year-old Naylor, whose torrid finish contributed to a 124 OPS+ over 230 plate appearances as a rookie in 2023, would be a big help.

Royals: Starting pitcher ERA

The Royals’ rotation ranked 27th in the Majors with a 5.12 ERA during the team’s 106-loss campaign a year ago, but their staff looks a lot different now than it did for much of 2023. It started with the acquisition of Cole Ragans in a trade with the Rangers for Aroldis Chapman last summer and continued with the free-agent additions of Seth Lugo and Michael Wacha this offseason. With Ragans looking like a potential ace for Kansas City after the trade and Lugo and Wacha both coming off solid seasons with the Padres, the Royals could have a much-improved rotation in 2024.

Tigers: Collective OPS from Spencer Torkelson and Riley Greene

Although the additions of Kenta Maeda and Jack Flaherty and a full season from Tarik Skubal could give the Tigers an improved rotation in 2024, they’re only going to go as far as their young bats can take them. After struggling as rookies in 2022, Torkelson and Greene both made significant strides last season, raising expectations entering ‘24. Detroit’s offense could also get a boost from infielder Colt Keith (MLB Pipeline’s No. 22 overall prospect), who appears to be on the verge of his MLB debut after inking a contract extension with the Tigers on Sunday.

Twins: Combined WAR from Carlos Correa and Byron Buxton

The Twins leaned on their pitching staff to win the AL Central in 2023, but with Sonny Gray and Kenta Maeda departing as free agents, Minnesota’s starting staff may not be as effective this season. As a result, the Twins need to get more out of Correa and Buxton, both of whom posted an OPS+ below 100 last season. The duo combined for just 2.2 WAR, only 0.8 of which came from Buxton, who didn’t play a single game on defense after undergoing right knee surgery in 2023. Correa and Buxton were both 4-plus WAR players one year prior, combining for 9.5 WAR.

White Sox: Combined PA from Luis Robert Jr., Yoán Moncada and Eloy Jiménez

Several years ago, Robert, Moncada and Jiménez looked like key members of an exciting young core for the White Sox, with all three players signing long-term extensions. However, the team has rarely had all three healthy and performing well at the same time. Robert had his long-awaited breakout last season, recording 38 homers, 20 steals and a 128 OPS+, but Moncada and Jiménez continued to deal with injuries and were both around league average at the plate. The latter two are now entering the final guaranteed year on their contracts. While Chicago is looking toward the future, seeing these three stay healthy and live up to their potential would be a big win for the club in 2024, even if it’s just to improve its standing leading up to the Trade Deadline.

AL WEST

Angels: Mike Trout’s games played

There’s nothing the Angels can do to replace two-way superstar Shohei Ohtani’s impact, but getting a healthy season from Trout would certainly help as the Halos look to turn the page after losing Ohtani to the Dodgers in free agency. Trout has missed more games (249) than he’s played (237) over the past three seasons and hasn’t appeared in more than 140 games since 2016.

Astros: Cristian Javier’s ERA

The Astros have made the AL Championship Series in seven straight years and just added All-Star closer Josh Hader to what was already a star-studded roster. But for all of Houston’s big names, it’s Javier who might have a sizable influence over how far the team goes in 2024. The right-hander was outstanding in 2022, posting a 2.54 ERA in the regular season and starting two combined no-hitters, including one in the World Series against the Phillies. He also started off strong last season, pitching to a 2.90 ERA over his first 14 starts. However, the right-hander struggled thereafter (6.20 ERA) and flopped in Game 7 of the ALCS against the Rangers, yielding three runs and failing to make it out of the first inning in Houston’s 11-4 loss. With a lot of uncertainty in their rotation behind Framber Valdez and Justin Verlander, the Astros are counting on Javier to return to form.

Athletics: Zack Gelof’s OPS+

The A’s lost more than 100 games for the second straight season in 2023, but they found a potential building block for the future in Gelof, a second-round pick in the ’21 MLB Draft. The 24-year-old debuted in mid-July and went on to produce a 137 OPS+ -- better than both Rookie of the Year Award winners, Corbin Carroll and Gunnar Henderson -- along with 14 homers and 14 steals in 69 games. It will be interesting to see what Gelof does for an encore.

Mariners: Runs scored per game

After posting the second-highest strikeout rate in the Majors last season, the Mariners replaced four of their most whiff-prone hitters -- Teoscar Hernández, Jarred Kelenic, Eugenio Suárez and Mike Ford -- with Mitch Garver, Mitch Haniger, Jorge Polanco and Luis Urías. Seattle’s new quartet combined for a 25.3% strikeout rate and 25.4% whiff rate last season, compared to a 31.1% strikeout rate and 33.8% whiff rate for the four hitters the team replaced. Whether those changes lead to more runs remains to be seen. The Mariners have one of the best pitching staffs in the game, but they averaged 4.68 runs per game in 2023, right around the MLB average of 4.62.

Rangers: Combined starts from Nathan Eovaldi and Jon Gray

It’s possible the defending World Series champions could still re-sign free agent Jordan Montgomery, but if they don’t, the onus is going to be on Eovaldi and Gray to stay healthy and carry the team’s rotation. The Rangers should have one of the best offenses in baseball once again, especially if prospects Evan Carter and Wyatt Langford live up to expectations as rookies. However, Texas’ starting staff could potentially hold back the club from vying for another title. The Rangers are not only without Montgomery but also won’t have Max Scherzer (back surgery) or Jacob deGrom (Tommy John surgery) until midseason at the earliest.

NATIONAL LEAGUE EAST 

Braves: Team postseason OPS 

Considering how big of an offensive powerhouse the Braves are, it's shocking how much they've struggled in the last two postseasons. Atlanta had a .594 OPS in the 2022 playoffs after ranking second in MLB with a .761 OPS in the regular season, and a .519 OPS in the 2023 playoffs after leading MLB with an .845 OPS in the regular season. If -- maybe when -- the Braves return to the postseason in 2024, a lineup with Ronald Acuña Jr., Matt Olson, Austin Riley, Marcell Ozuna, Ozzie Albies, Michael Harris II, Sean Murphy and Jarred Kelenic has to be better.

Marlins: Luis Arraez's batting average 

Arraez's quest for .400 was one of the most fun storylines of the 2023 season. Even though he finished the year at "only" .354, it was still great to watch such a throwback style of contact hitter go basically wire-to-wire to win the MLB batting title and help the upstart Marlins reach the postseason. Let's hope for another .400 chase in 2024.

Mets: Edwin Díaz's saves

The disaster that was the Mets' 2023 season began even before Opening Day, when their superstar closer tore the patellar tendon in his right knee in a freak injury celebrating during the World Baseball Classic. Well, Díaz is back, and if the Mets are going to be any sort of contender in 2024, he's going to have to recapture his electricity from 2022, when he had 32 saves, a 1.31 ERA and an incredible 118 strikeouts in 62 innings.

Nationals: CJ Abrams' home run/stolen base total

The Nats' Juan Soto trade will look a lot better if Abrams keeps playing like he did over the second half of the 2023 season. The 22-year-old hit 11 home runs and stole 33 bases in 70 games after the All-Star break -- which is a ridiculous 25-homer, 75-steal pace for a full season. With a power-speed combo like that, Abrams would be a rising star at shortstop in the NL.

Phillies: Zack Wheeler and Aaron Nola's combined WAR

If the Phillies want to compete with the juggernaut Braves in the NL East and make another deep postseason run, their pair of aces have to lead the way. Since the 2020 season, when Wheeler joined Nola in Philadelphia, no duo of starting pitchers has been more valuable. Wheeler leads all pitchers in Wins Above Replacement over that time (19.3), per FanGraphs, and Nola ranks fourth (16.6). And they're both projected to be top-five MLB aces again in 2024.

NL CENTRAL

Brewers: Team home run total

The Brewers won the Central in 2023, but they did it with one of the league's weakest offenses, finishing in the bottom 10 in the Majors in slugging percentage (.385), OPS (.704), OPS+ (93) and home runs (165). They were the worst playoff team in all of those categories. But Milwaukee's signing of Rhys Hoskins (30 homers in his last season in 2022) and the arrival of MLB's No. 2 overall prospect Jackson Chourio (22 homers in the Minors last year) should help address that power deficiency in 2024.

Cardinals: WAR from players under 25

The Cardinals have been led by their veterans for a long time -- and they still have that leadership in superstar duo Paul Goldschmidt and Nolan Arenado -- but after last year's jarring last-place finish, St. Louis will need its young guns to rise up in 2024. Keep your eyes on three players in particular: 23-year-old Nolan Gorman (27 home runs, 117 OPS+ last season), 21-year-old Jordan Walker (16 home runs, 114 OPS+) and 21-year-old Masyn Winn (the Cardinals' No. 1 prospect and MLB's No. 43).

Cubs: Pete Crow-Armstrong's hits total 

The Cubs have the most Top 100 prospects of any team entering 2024, and Crow-Armstrong is at the top of their list as MLB's No. 16 prospect overall. The 21-year-old outfielder is an elite defender with top-of-the-line speed, and he showcased both of those tools in his brief big league callup at the end of last season. But at the plate, PCA went 0-for-14, so he enters 2024 still seeking his first MLB hit. That hit will come, and if Crow-Armstrong's bat catches up to his glove and his wheels, he could quickly take over center field in Chicago.

Pirates: Paul Skenes' debut date

The Pirates will have plenty of good young players in the lineup this season -- Oneil Cruz, Jack Suwinski, Ke'Bryan Hayes, Henry Davis and so on. But the most exciting name hasn't arrived yet. That's Skenes, baseball's most prodigious pitching prospect since Stephen Strasburg. The 21-year-old right-hander, who was the No. 1 overall pick in the 2023 Draft and is ranked MLB's No. 3 prospect entering the season, could make his MLB debut at some point in 2024. When that day comes, the hype will be incredible. And if Skenes is pitching for the Pirates this year, it might mean Pittsburgh is in contention.

Reds: Games played by players in their first three seasons

Joey Votto's departure is symbolic of a changing of eras in Cincinnati. The Reds' youth movement is here. Nearly every key player for Cincinnati has just recently reached the big leagues: Elly De La Cruz, Matt McLain, Noelvi Marte, Andrew Abbott and Christian Encarnacion-Strand are all entering Year 2, and Hunter Greene, Nick Lodolo, Alexis Díaz, Spencer Steer and Will Benson are entering Year 3. This 2024 Reds team is all about potential.

NL WEST

D-backs: Corbin Carroll's stolen bases

Carroll is already one of the best players in baseball. What could be the next step for a phenom who just had a 25-homer, 54-steal season, ran away with the NL Rookie of the Year, was a top-five MVP finisher and led his underdog team to the pennant, all at age 22? Well, how about challenging Rickey Henderson for stolen base history? Carroll's combination of elite speed, skillful baserunning and role at the top of the D-backs' order makes him possibly the only player who could break into the stratosphere of Rickey's single-season stolen base record of 130. And wouldn't that be something to see? There should only be one thing on Carroll's mind in 2024: Run.

Dodgers: Starting pitcher ERA 

Los Angeles invested heavily in its starting rotation this winter -- bringing in Yoshinobu Yamamoto, Tyler Glasnow and James Paxton -- and it's not hard to see why. Despite their 100 wins, the Dodgers ranked 20th in the Majors in starting pitcher ERA in 2023 (4.57), and things got even worse in the postseason, when Dodgers starters allowed 13 runs in just 4 2/3 total innings in their three-game sweep by the D-backs. With Yamamoto, Glasnow, Paxton and the return of Walker Buehler in 2024, things should be different.

Giants: Jung Hoo Lee's batting average

The Giants' marquee signing of the offseason was landing the KBO superstar Lee, who was a career .340 hitter in seven seasons in Korea and is still just 25 years old. It's the second straight season an elite international contact hitter will come to the Majors after Masataka Yoshida signed with the Red Sox from Japan in 2023, and Lee will look for similar success in San Francisco. The 2024 projections are high on Lee -- Steamer projects him to finish top-10 in the MLB batting race, with the second-lowest strikeout rate in MLB behind only Arraez.

Padres: Michael King's ERA

For the last several years, the Padres relied on their Big Three of Blake Snell, Yu Darvish and Joe Musgrove to lead the starting rotation. But Snell is a free agent, fresh off winning the NL Cy Young Award, and King is the pitcher who'll have to step up to replace him. King was the prize of the Juan Soto trade with the Yankees, and he was dominant last season. The 28-year-old had a 2.75 ERA and 127 strikeouts in 104 2/3 innings, including a 1.88 ERA and 48 K's in 38 1/3 innings over eight starts down the stretch, when the Yankees moved him into the rotation.

Rockies: Nolan Jones' OPS+

The most promising player the Rockies have right now is Jones, who posted big numbers as a rookie last season: a .297/.389/.542 slash line, .931 OPS and 138 OPS+, with 20 home runs and 20 stolen bases in 106 games. The 25-year-old lefty slugger looked great once Colorado finally got him into the lineup at the end of May, and there'll be no holding him back in 2024. Jones is the best all-around hitter on the team and could be a breakout star in the NL West if he puts up the same type of numbers over a full season.