Fun fact: Earned Run Average (ERA), the statistic that is almost always the first cited as a measurement of an individual pitcher’s performance, was originally used to measure a team’s offensive performance. ERA was used to measure how many runs a team’s offense “earned” through their batting, without the benefit of the opposing team’s bad defense.
Put a pin in that, we’ll come back to it in a minute.
Mark Leiter Jr. has been a damn good relief pitcher in 2025. (For those of you who were with me at the time, that statement should carry some weight because I was not a fan of his acquisition.) The answer to the question, “Who has been the best Yankees relief pitcher this season?” is clearly Fernando Cruz or Leiter, as their under the hood numbers are very similar.
League wide, there have been 137 relief pitchers who’ve thrown at least 30 innings in 2025.
Among those 137 pitchers, Leiter ranks in the top 10 in expected FIP, average exit velocity allowed, and hard-hit percentage allowed. He’s been one of the hardest pitchers in baseball to make hard contact against, and when contact is made, he’s far above average (29th out of 137) at keeping the ball on the ground.
He also ranks 19th out of 137 in K-BB% so even when contact is not made, he’s been excellent at missing bats and not issuing free passes.
That’s not just one of the best on the Yankees, that’s one of the better relievers in MLB.
But…
Despite the above, he’s watched 42% of the balls hit against him to become hits. If you’re wondering, yes – his .419 BABIP against is the highest in MLB. As Crash Davis said, sometimes there are just a lot of dying quails and ground balls with eyes. Also, as James Smyth pointed out recently, the Yankees defense has been inexplicably awful at getting to batted balls when Leiter is on the mound.
You were saying something about ERA…
Despite being great at missing bats, yielding soft contact on the ground, and not issuing free passes – the only things a pitcher can control – Leiter’s 4.18 ERA is the second worst on the Yankees, and the 102nd worst among the 137 MLB relievers noted above.
And that ERA has nothing to do with his performance. It’s comical bad luck – batters are tapping the ball on the ground but have a .419 BA against him – and defenders that don’t get to batted balls.
Always, always, look at what the pitcher is doing or not doing – don’t pay too much attention to the result that has factors beyond the pitcher’s control.
Start by ignoring ERA.
Did I miss something? Let me know in the comments, or yell at me on the “My Baseball Page” on Blue Sky.
Recommended reading: “The Numbers Game” by Alan Schwarz. It’s where I got the above referenced tidbit on ERA and tons of other great information about the numbers in our game.
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