Jesus Montero was acquired by the Mariners because the Mariners, like so many other people, figured he could blossom into one hell of a bat. The Mariners also figured Montero could catch, which would be great, but even if Montero had to play first or DH, the Mariners liked his potential, because everyone has always liked Montero's potential. Okay. Fast forward!
If you want to be encouraged, 192 players this season have enough at-bats against left-handed pitchers to be considered "qualified," whatever that means. Montero's numbers are the 14th-best, by one reasonable measure, and some of the names around him are David Freese, Billy Butler, Yadier Molina, and Mike Trout. Montero has hit lefties. Montero has humiliated lefties.
If you want to be discouraged, 164 players this season have enough at-bats against right-handed pitchers to be considered "qualified," whatever that still means. Montero's numbers are the second-worst by the same measure. The second worst! Out of everybody! He's been better than Clint Barmes. A lot better than Clint Barmes. Worse than everyone else. Worse than whoever Brian Dozier is. Worse than everyone else. Way worse than Justin Smoak. Worse than everyone else.
The ability is there, and Montero has shown it against southpaws. He can destroy pitches like few others. It's good to know that all of the scouting evaluations were not incorrect. The consistency is not there, because Montero has been helpless against righties. Going over Montero's recent performance is hysterical in its predictability. 10-for-17 in a four-game series against the Royals, with all four games started by lefties. 0-for-4 last night in a game started by a righty. 2-for-3 with a homer and a walk a few days ago in a game started by a lefty. 0-for-5 against righty James Shields and the Rays. 2-for-4 against lefty Matt Moore and the Rays. And so on. Good against lefties. Bad against righties.
Everybody expects that players will have platoon splits - that's why we're aware of the term "platoon splits" - but Montero has taken things to the extreme. He's been a caricature of a guy who can hit a fastball, but who's left weak in the knees versus a breaking ball breaking away. Breaking balls breaking away aren't Montero's whole problem, but they're something that righties can throw him, and that lefties cannot.
Before we go much further, it's absolutely critical to be aware of the sample sizes. Montero has just 367 plate appearances this season, and 436 plate appearances in his big-league career. 285 against righties, 151 against lefties. These sample sizes are very small. They might not seem small, because they number in the hundreds, but they are small, for purposes of establishing a true-talent baseline. I would assume that Montero is better than his numbers against righties, and the opposite of that against the opposite of that. But still, we can investigate. Small sample sizes don't mean "stay away"; they mean "proceed with caution." A small sample size is a yellow light. No, that doesn't work, people speed through yellow lights recklessly. A small sample size is a yield sign, or railroad tracks. Better make sure there's nothing on the railroad! Don't want to end up dead! From making too much of a small sample size.
We can look for things that might be more meaningful than general platoon splits. Let's combine Montero's time with the Yankees with his time with the Mariners because there's no sense in splitting them apart. Some numbers.
Montero vs. righties:
Strike rate: 67%
Contact rate: 75%
Montero vs. lefties:
Strike rate: 64%
Contact rate: 81%
Nothing too surprising in there. Montero does a little better job of controlling the zone against southpaws, and he makes more frequent contact. Fewer breaking balls, remember. Most of that extra contact has gone to foul balls, but the in-play contact has been better. Here's what I'm talking about, and here's probably the most important split:
Montero vs. righties:
Groundball rate: 47%
Montero vs. lefties:
Groundball rate: 32%
Most righties hit more grounders against righties than they do against lefties. Most righties do not show this kind of difference. Ball-in-play rates stabilize pretty fast and Montero has 110 balls in play against lefties and 201 balls in play against righties, so while you could regress those some, this is a significant difference.
If you'd like, you could say that the difference is almost entirely line drives - Montero's fly ball rates are virtually identical. But I don't like trying to separate fly balls from line drives. I figure there are grounders and non-grounders, and Montero has hit way more non-grounders against southpaws, allowing him to destroy them.
Montero is a power hitter, see, and not a speedy hitter, so in order to be productive he needs to put the ball in the air. We've seen him run. It's unpleasant to see him run. Much more pleasant to see him trot, which goes at about the same speed. Montero's groundball rate against righties is too high for my liking. It wouldn't be impossible for him to succeed at 47% grounders, but it would be a challenge. The running. Jesus Montero's career BABIP on grounders is going to be .020.
For Montero, I don't have much of a minor-league track record to look up. I can only see what he did with triple-A Scranton/Wilkes-Barre in 2011. Against lefties, he put 28 of 93 balls in play on the ground, or 30%. Against righties, he put 112 of 232 balls in play on the ground, or 48%. That is a huge split. His OPS split was more than 300 points. The major-league average OPS split this year for righties against righties and lefties is 44 points. Jesus Montero is weird.
Think about Mariners you recall having trouble with low-and-away breaking balls as righties. Jose Lopez's career splits are normal. Adrian Beltre's career splits are normal. Miguel Olivo's career splits are very wide, but far less wide than Montero's. Olivo has hit far better against lefties than righties, but I wouldn't say that's a selling point. Seven out of every ten plate appearances for Olivo have come against righties. Over those plate appearances, he's posted a .263 OBP.
Jesus Montero, since the start of 2011, has shown very broad platoon splits. Against lefties, he's been an all-world slugger, making enough contact and driving the ball in the air. Against righties, he's been disgusting, and nearly half of his balls hit in play have been on the ground. That's not who Jesus Montero is. Correction: that is who Jesus Montero is, but that isn't what Jesus Montero is supposed to be. Montero is an unfinished product in plenty of ways, and this is one of them. Montero needs to improve against right-handed pitchers. The majority of pitchers he's going to face will be right-handed pitchers, and he'll be expected to be an everyday, middle-of-the-order contributor. What'll go into making Montero better? Hell, I don't know. I'm not a hitting coach, and I don't even know what hitting coaches do. But this is an important project. Whatever is the matter with Jesus Montero against righties needs to stop being so much the matter. Until he can drive the ball in the air regardless of pitcher handedness, he'll be only an occasional bat, and that isn't the point of Jesus Montero at all.