Each new season brings new challenges. But challenges are nothing new to those on the list below.

These players -- including some of MLB's very best -- have experienced tough times and bad breaks in recent years. Some have been bitten by the injury bug. Others have fallen short of expectations. Maybe you've begun to doubt some of them, but they are all integral to their respective team's success in 2024. All they have to do is perform up to their capabilities. 

Here are 11 players with something to prove this season.

Chris Sale, LHP, Braves
Sale is sort of the ultimate risk-reward acquisition for the Braves. With him, their starting rotation can stand toe to toe with any in baseball. A healthy Sale as your No. 3 starter? That's a sign of a deep staff. Plus, his two-year extension provides Atlanta with a little bit of short-term stability if the team loses left-hander Max Fried as a free agent next offseason.

But the past four years have been anything but stable for Sale. A spate of injuries -- left elbow inflammation, Tommy John surgery, right rib stress fracture, fractured left pinkie finger, broken right wrist, left shoulder blade stress fracture -- have limited him to only 151 innings since August 2019. There were still flashes of greatness from him last season, highlighted by a stellar 29.4% strikeout rate over 102 2/3 innings, and there are things he can do to improve moving forward. But for this trade to work out for the Braves, they need Sale to do something he hasn't done often recently: stay on the mound.

Trevor Story, SS, Red Sox
In return for Sale, Boston received Vaughn Grissom, who will be immediately installed as Story's new double-play partner. Story was brought aboard prior to the 2022 season after clobbering at least 24 homers in each of his first five full big league seasons and recording a 120 OPS+ in four of those years. He also sat out a total of 60 games from 2017-21. In '22, he missed 68 games due to injuries and saw his overall production slide (102 OPS+).

In 2023, the bottom fell out. Story was sidelined for the first four months of the season as he recovered from right elbow surgery. Upon his return, he posted a paltry .203/.250/.316 slash line (52 OPS+) across 43 games. His strikeout rate rose to 32.7% while his walk rate was a career-worst 5.4%. Story still has good wheels, a dependable glove and did register a 42.7% sweet-spot rate last year, fifth-best among hitters with a minimum of 150 plate appearances. But heading into Year 3 of his six-year, $140 million contract, Story needs to be a vital cog in Boston's lineup.

Shane Bieber, RHP, Guardians
Bieber has ostensibly been on the trade block since the middle of last season. Right elbow inflammation scuttled any chance of a deal prior to the 2023 Trade Deadline, and despite being the subject of trade rumors throughout the offseason, Bieber remains with Cleveland ahead of a pivotal year for him and the team.

If health is on his side, Bieber can lead what looks like a promising rotation in a very winnable AL Central. Although he may never rediscover his 2020 American League Cy Young form -- especially as his fastball has since lost 3 mph of velocity -- the 28-year-old is still an above-average starter. And if the Guardians fall out of the division race, they could again dangle Bieber as a valuable trade chip this summer. Meanwhile, a bounceback year would increase Bieber's outlook as a free agent next offseason. But he will first have to show that his career-worst 20.1% strikeout rate and glaring hard-hit rate last year were just a blip.

Vladimir Guerrero Jr., 1B, Blue Jays
What kind of hitter is Vlad Jr. at this stage of his career? Is he the hitter who backed up his "can't-miss prospect" hype by missing hardly anything thrown to him in 2021 as he bashed 48 dingers and was the AL MVP runner-up? Or is he simply more of a reliably productive bat? His numbers last season -- 26 home runs, 117 OPS+ -- are not terrible by any means; they just don't meet the expectations for a player who was arguably MLB's top hitter at 22 years old.

Now entering his age-25 campaign, Guerrero may still have his best baseball in front of him. While his 2023 results were kind of confusing, Guerrero's plate skills and expected stats hint that he can be that elite, feared slugger once again. That's what the Blue Jays need from him if they are going to hit their ceiling.

Tyler Glasnow, RHP, Dodgers
You could put Yoshinobu Yamamoto in this spot, but we'll give Los Angeles' $326 million starter a break as he hasn't fired a single pitch in the Majors yet. When Glasnow is able to fire, he can baffle batters all day long. His 35.3% whiff rate and 33.4% K rate respectively ranked in the 96th and 97th percentile last year. His 2.91 FIP trailed only Spencer Strider and Sonny Gray among starting pitchers (min. 100 IP).

The only question surrounding the oft-injured Glasnow is: Can he push past the career-high 120 innings he threw last season? No team is making a bigger effort to win the World Series than the Dodgers, but their rotation has enough uncertainty as is. That includes Yamamoto's clean slate, Shohei Ohtani's unavailability and Walker Buehler's return from Tommy John, to name a few concerns. The last thing they need is for Glasnow to break down again. His health will be key to the club's championship hopes.

Nestor Cortes, LHP, Yankees
Cortes had a 6.72 ERA and a 1.71 WHIP through his first three Major League seasons, which included an initial stint with the Yankees in 2019. There was no reason to expect that this left-hander would turn into a Cy Young contender in short order, but the Cortes experience -- fit with funky windups and his trademark mustache -- took the league by storm in 2022. He logged a 2.44 ERA across 158 1/3 frames and finished eighth in the AL Cy Young voting.

His plans for a repeat were sidetracked almost immediately by a hamstring strain suffered in Spring Training. That might have played a part in his poor early-season results, featuring a 5.16 ERA through his first 11 starts. Cortes then made only one start over the season's final four months before being shut down with a left rotator cuff injury. The addition of Marcus Stroman and the focus on high-priced left-hander Carlos Rodón will draw some attention away from Cortes, but he has to prove that one amazing year wasn't a fluke.

Byron Buxton, CF, Twins
What we wouldn't give to see another full season of Buxton playing freely. Alas, one of baseball's most dynamic players has suited up for 100 games only once in nine years, so perhaps that's unlikely. The former Platinum Glove winner was relegated to DH duty last year as he dealt with pain in his right knee throughout. He didn't play after Aug. 1 and then underwent surgery on that knee for the second straight offseason.

The Twins are going to put Buxton back in center this year, but it's fair to wonder how much his body can handle as he enters his age-30 season. At the plate, Buxton recorded a 98 OPS+ last season after averaging a 136 OPS+ from 2019-22. He also saw his K rate finish above 30% for the second year in a row. There are some good signs in his profile -- he still has plenty of raw power and is drawing walks much more frequently than in his younger days -- but can he last in center field and be something more than a three-true-outcomes slugger? It would be a boon for the Twins.

Jazz Chisholm Jr., CF, Marlins
Speaking of players who are extremely fun to watch when they are operating at 100%, Chisholm is going through injury rehab for the second consecutive offseason. He played only 60 games in 2022 because of a back strain. He also dealt with a right knee injury that he said he suffered in Spring Training but played through until going under the knife that September. He saw action in 97 games this past season and is currently recovering from toe surgery.

Although his batting eye needs a lot of refinement, Chisholm has some natural, face-of-the-franchise skills. His sprint speed ranked above the 90th percentile in 2021 and 2022, and not just anyone can deposit a triple-digit heater from Jacob deGrom into the upper deck. Consider that the Marlins have two 30-homer, 30-steal seasons in their 31-season history. Chisholm's 162-game average over the previous three years includes 29 homers and 33 steals. As he turns 26 years old next month, Chisholm needs to make the most of his prime years.

John Means, LHP, Orioles
At the beginning of the offseason, the Orioles knew they needed to add a frontline starting pitcher. With less than a month to go before Spring Training begins, the Orioles still need a frontline starting pitcher. Even if they don't add someone on the level of Dylan Cease or Blake Snell or Jordan Montgomery, Baltimore must find someone who can cover the 192 innings that Kyle Gibson, now with the Cardinals, contributed in 2023. Means could be that guy.

The left-hander was an All-Star in his 2019 rookie year and threw a no-hitter during his mostly successful 2021 season. However, Means tossed only eight innings the following year before undergoing Tommy John surgery. He returned with 23 2/3 frames last September, but soreness in his surgically repaired elbow kept him off the team's playoff roster. Means may be on an innings count in 2024, his final season before becoming a free agent. The Orioles would love to see those innings resemble something close to what he provided earlier in his career. But it's hard to tell if he is still that kind of pitcher with so few post-TJ innings under his belt.

Ty France, 1B, Mariners
Seattle, like Baltimore, has an evident need as well, but it resides at the plate, not on the mound. The Mariners could use one more dangerous bat after non-tendering Teoscar Hernández and trading away Eugenio Suárez. While France doesn't possess as much long ball pop as those two, he was a force not too long ago. From the start of August 2021 through July 2022, France produced a solid .311/.385/.476 slash line through 638 plate appearances.

From that date, France has a .242/.319/.366 line through 890 plate appearances. His penchant for getting hit by pitches -- his 82 HBPs over the past three seasons are 10 more than any other player -- may have something to do with the prolonged slump. It may also be a bit of bad luck as France's plate discipline is still very good, and he finished far behind some of his expected stats. Regardless, Seattle's lineup would look much more complete if it knew what type of production it was getting from its first baseman this season.

Michael Conforto, LF, Giants
Conforto's first season in San Francisco began well enough as he put up 12 dingers and an .823 OPS through his opening 53 games. But after June 8, there was hardly any life in his bat. He hit only three home runs through the rest of the season, and his .317 slugging percentage was sixth lowest among all hitters (min. 250 PA). He was a far cry from the player who averaged a .459 slugging with the Mets from 2017-20. His barrel rate (7.9%), maximum exit velocity (109.7 mph) and sweet-spot rate (31.9%) were career lows. And Conforto, who is no stranger to injury, missed three weeks down the stretch with a strained left hamstring.

He could have hit the open market again this offseason, but Conforto decided not to opt out of the second year of his deal. He will hope to rebound in 2024 as the Giants' starting left fielder. However, given his power outage and declining outfield defense, Conforto's career might be at a crossroads at age 31.