With the excitement of the postseason on deck, it's time to look at which players led MLB and their respective leagues in key statistical categories during the 2018 regular season, ranging from traditional Triple Crown categories to the latest Statcast™ metrics.
Four National League teams will play in one-game tiebreakers today that will determine the division champion in the NL Central and NL West: The Brewers will play the Cubs at Wrigley Field (1 p.m. ET, ESPN) and the Rockies will play the Dodgers at Dodger Stadium (4 p.m. ET, ESPN). The statistics from those games will count toward regular-season totals, meaning that Milwaukee's Christian Yelich could still win the first NL Triple Crown in 81 years. The NL RBI title will be decided in at Wrigley Field, with Chicago's Javier Baez (111) leading Yelich by two in that department.
Here's a look at the leaders in each category this season:
BATTING
Home runs: MLB/AL -- Khris Davis (48): Davis set a career high in homers, besting the 43 he hit last season. Over the last three seasons, Davis has launched 133 homers for the A's. Boston's J.D. Martinez finished second, with 43 home runs.

NL -- Nolan Arenado (37): Arenado clubbed his 36th and 37th homers of the season on Sunday against the Nationals, overtaking the leaders entering the day, Yelich and Matt Carpenter. If he ends up with the home run title after today's action, it will be the third time in Arenado's six-season career he has led or tied for the league lead in homers. Yelich, Carpenter and Trevor Story, Arenado's teammate, are all tied with 36. Should Yelich, Arenado and/or Story homer in today's tiebreaker games, those stats would count toward regular-season totals.
Batting average: MLB/AL -- Mookie Betts (.346): Betts had a tremendous season that put him squarely in the American League Most Valuable Player conversation. His .346 clip was the highest in baseball and a career high. His Red Sox teammate, Martinez, finished second in the Majors and AL with a .330 average.

NL -- Christian Yelich (.323): Yelich still has a chance to win the NL's first Triple Crown since 1937, thanks to today's tiebreaker game for the NL Central title. He has won the NL batting average title with his .323 clip, while he's one off the pace in homers and two off the pace in RBIs. The Reds' Scooter Gennett is the runner-up in NL batting average at .310.
RBIs: MLB/AL -- J.D. Martinez (130): Martinez, himself chasing a Triple Crown for much of the season, finished with 130 RBIs to lead the Majors. Davis finished second, with 123.

NL -- Javier Baez (111): Baez has a two-RBI lead over Yelich heading into the Cubs-Brewers NL Central tiebreaker. He has had a big season, setting career highs in RBIs as well as doubles (40), triples (9), home runs (34), runs scored (101) and steals (21).
Yelich only needs to equal Arenado's and Baez's totals to earn the Triple Crown; he does not need to pass them.
Stolen bases: MLB/AL -- Whit Merrifield (45): Merrifield stole two bases on Saturday to overtake the Nationals' Trea Turner for the MLB lead. His 45 steals are a career high, eclipsing the 34 he stole in 2017, which were an AL high that season. The Rays' Mallex Smith finished second with 40.

NL -- Trea Turner (43): Turner swiped 43 bases in 52 attempts on the season to lead the NL, and has 124 steals in 360 career games. The Reds' Billy Hamilton finished second with 34 steals.
On-base percentage: MLB/AL -- Michael Trout (.460): Trout put together another monster year, a central part of which was a .460 OBP that led the AL for the third consecutive season. Betts finished second in the AL with a .438 OBP.

NL -- Joey Votto (.417): Votto led the NL in OBP for the seventh time in a 12-year career. The Mets' Brandon Nimmo was the runner up with a .404 OBP.
Slugging percentage: MLB/AL -- Betts (.640): Mookie was an extra-base machine in 2018, hitting 47 doubles, five triples and 32 homers. Martinez and Trout were close behind, at .629 and .628, respectively.

NL -- Yelich (.596): The Brewers star outslugged everyone in the Senior Circuit, with 34 doubles, seven triples and 36 homers heading into today's tiebreaker against the Cubs. Story, also playing in a tiebreaker game today against the Dodgers, is second in the NL at .564.
Statcast™ barrels:MLB/AL --  Khris Davis and J.D. Martinez (69): Davis and Martinez also finished tied for second in the Majors in percentage of plate appearances with a barrel (10.6).

NL -- Manny Machado (60): Machado had 39 barrels with the Orioles, and then 21 after being traded to the Dodgers at the All-Star break. Both he and Yelich, who has 57, will have a chance for more today. Paul Goldschmidt also finished the season with 57.
PITCHING
Wins: MLB/AL -- Blake Snell (21): Snell had a breakout season and is a strong candidate to win the AL Cy Young Award. Indians right-hander Corey Kluber finished with 20 wins, winning 20 for the first time in his eight-year career.

NL -- Max Scherzer, Jonathan Lester, Miles Mikolas (18): A trio of pitchers finished tied for most wins in the NL. Mikolas picked up his 18th victory over the weekend against the Cubs at Wrigley Field to join Scherzer and Lester.
ERA: MLB/NL -- Jacob deGrom (1.70): deGrom had one of the greatest individual seasons by a starting pitcher in baseball history, posting a 0.91 WHIP and limiting opposing batters to a .196 batting average. And in an era during which record numbers of home runs are being hit around the Majors, deGrom gave up only 10 out of 835 batters faced. The Phillies' Aaron Nola finished second in the league with a 2.37 ERA.

AL -- Blake Snell (1.89): Snell finished with a 0.97 WHIP and held opponents to a .178 average in a dominant season that may land him the AL Cy Young Award. The Indians' Trevor Bauer, who had a breakout year of his own, finished second with a 2.21 ERA.
Strikeouts: MLB/NL -- Max Scherzer (300): Scherzer hit the 300-strikeout milestone for the first time in his illustrious career, and remarkably, gave up exactly half that number in hits as he seeks his fourth career Cy Young Award. deGrom's 269 strikeouts were second in the NL.

AL -- Justin Verlander (290): Verlander continues to defy his age (35), setting a career high in strikeouts in 2018. He also posted a 2.52 ERA and 0.90 WHIP. His teammate in the Astros rotation, Gerrit Cole, finished second in the AL with 276 punchouts.
Saves: MLB/AL -- Edwin Diaz (57): Diaz tied Bobby Thigpen (1990 for the White Sox) for the second-highest single-season saves total in Major League history. He converted 57 of 59 save chances on the season for the Mariners (96.6 percent).

NL -- Wade Davis (43): Davis has had his ups and downs in 2018, posting a 4.13 ERA in his first season with the Rockies heading into today's tiebreaker. But he still managed to convert 43 saves to lead the NL. His counterpart today, Kenley Jansen, is second with 38.
FIELDING

5-star catches: MLB/NL -- Harrison Bader (7): The Cardinals rookie impressed both at the plate and in the field, making seven 5-star catches (catch probability of 25 percent or lower) and also making very difficult plays look easy in the outfield. The Brewers' Lorenzo Cain was second, with six 5-star catches this season.

AL -- Delino DeShields (5): DeShields put his speed to great use while patrolling center field for the Rangers this season. Kevin Kiermaier, Jackie Bradley Jr. and Max Kepler each finished with three 5-star catches in 2018.
Outs above average: MLB/NL -- Harrison Bader (21): Bader also led the Majors in outs above average, which is a range-based metric of fielding skill that accounts for the number of plays made and the difficulty of them. Ender Inciarte was right behind him, with 20 OAA.

AL -- Adam Engel (17): After finishing second to Byron Buxton in OAA last season (Engel had 17 to Buxton's 20), Engel led the AL in 2018.