2018's biggest surprise statistical leaders

September 19th, 2018

I know certain stats like batting average, RBIs and wins have grown a bit out of fashion, and I understand why: It's progress in baseball thinking, which is always positive. But I'll confess: I'm a sucker for a baseball leaderboard. Wins Above Replacement (WAR) is the most efficient, effective stat, and Fielding Independent Pitching (FIP) tells us more about what's going on than our eyes can necessarily see, but I collected enough baseball cards and read enough old Baseball Encyclopedias to appreciate guys who lead the league in triples, batting average or walks. It's some good old-fashioned Baseball Reference black ink.
We have only a week and a half (!) left in the regular season, and if you've been more compelled by the actually pretty riveting fWAR chase between and (both right at 9.2), you might have missed some of the unusual statistical leaders in some major and semi-major categories this year. It might seem like Betts, Trout and are leading in everything. But you'll never believe some of the following league leaders.
, National League Adjusted OPS-plus leader: 151
Nimmo is in a virtual tie with , which is rather stunning, right? (This is OPS-plus adjusted for the player's ballpark, by the way.) Nimmo has been fantastic for the Mets this year -- he's a top 30 fWAR player -- and is one of the main reasons they've been so good for the past month. If Yelich ends up passing him, Nimmo also leads the NL in another category: Hit-by-pitches.

Whit Merrifield, American League stolen bases leader, 36
It may say more about the stolen base in the year 2018 that a player like Merrifield can lead the league in steals for two consecutive years, but he has upped his total this year and has a chance at 40. Merrifield, who I contend would be a legend throughout baseball if he had just joined the Royals a year earlier and been on that World Series-winning team, has raised his OBP more than 40 points this year and is hitting over .300. Thirty-six is still way too few steals to lead your league with.

, NL BB/9 leader, 1.41
When Mikolas was last in the Majors, back in 2014, he was known for being sort of wild; he averaged nearly a walk every two innings with San Diego in 2012-13. But his three years in Japan clearly fixed that problem. Mikolas, who has a chance to become the first Cardinal to win 18 games since in 2014, still doesn't strike out a ton of hitters, but when you avoid putting guys on with walks, you have a greater margin for error. (He also has only given up 15 homers in 185 2/3 innings.) Mikolas remains one of the best free-agent signings of the offseason for any team.

, NL starts leader, 32
Chacin has never been a fantastic pitcher -- he's only had an ERA under 3.50 over a full season twice, and he has never made an All-Star roster -- but you can always count on him going out and taking the ball every fifth day. On a team like the Brewers, a team that has needed all the starting pitching help they can get, that has been invaluable. Chacin has been perfectly fine this year, too, with a 3.54 ERA, 14 wins and, notably, the second-lowest FIP of his career. Chacin's next start will be the 200th of his career, which is more than, say, , , and . There is value in that.

, AL Win Probability Added leader, 6.1
's eye-popping save total has drawn much of the attention, but boy, Treinen has been just unbelievable this year. Forget the 37 saves and just look at that 0.85 ERA and the accompanying 1.86 FIP. His 4.48 K/BB ratio is dominating, and he has only given up two homers all season. And as evidenced by his 63 appearances, Oakland isn't just using him as a traditional closer either. In nearly every pivotal situation, Treinen has stepped up for the A's, and he's one of the primary reasons they're about to play their first postseason game since 2014.

, NL AB/HR leader, 11.1 AB/HR 
Muncy had five Major League homers coming into this season, and he hadn't hit one since Aug. 11, 2016. He wasn't on the Dodgers' Opening Day roster. Muncy didn't even warrant a paragraph in the 2018 Baseball Prospectus Annual. (He got one line, saying his bat would "max out" in Triple-A.) And now here he is, hitting a homer every 11.1 at-bats, which, spanned out over a full career, would be the second-highest ratio in baseball history (behind only Mark McGwire). Muncy also walks a ton. Guys like this just fall from the sky in Los Angeles sometimes. And he's the most unlikely guy to lead any category … maybe in years.

Scooter Gennett, NL batting average runner-up: .316 (Yelich, .317)
Why did we sleep on Gennett so long? Is it because his name is Scooter? (It might be because his name is Scooter.) Gennett had his breakthrough season in 2017 -- including his famous four-homer game against St. Louis -- but he has been even better in 2018, sacrificing a little power but more than making up for it in batting average and on-base percentage. If he can claim the batting title -- the red-hot Yelich is just ahead of him -- he'll become the first Red to win the NL batting crown since Pete Rose in 1973.