Why did Mike Leake get bad?

When the Giants acquired Mike Leake in July, they thought that he would help stabilize a shaky rotation. And after he came back from injury, they were right! Bumgarner was good, Peavy was pretty good, and everyone else, including Leake, was bad. It was very stable. Shoulda been more specific when you met that genie, Evans. Let that be a lesson to you.

But Mike Leake really shouldn't have been that bad. Throughout his whole career, he'd been a decent pitcher in an extreme hitter's park, so it stood to reason that moving to San Francisco, which park factors say turns Mike Trout into a literal trout, would help him out. That, of course, didn't happen. But why? What went wrong?

Oh.

Mike Leake came to the Giants, got worse at striking guys out than late-90s Kirk Rueter (I checked!), pitched badly, and, not being a human rabbit's foot, lost a bunch of games. Baseball analysis is simple and easy! No wonder everyone wants to get into it.

Of course, that's not the only thing Leake did worse with the Giants. Just two columns over, you can see his HR/9 rate, which shot up to heights not seen since his awful 2012. Three columns past that, you really start to see an anomaly: way more of the fly balls Leake gave up went for homers than they had throughout his career. Except for 2012, he had always given up homers on about 13% of fly balls. And then, moving to the most extreme pitcher's park for home runs in baseball, that rate went up. That would have been impossible to predict before the trade.

So why did that happen?

Looking at TEH STATZ, the main culprit would seem to be his sinker. It's his main pitch – Brooks has it as his only fastball, while Fangraphs says he also rarely throws a four-seamer – and its effectiveness dropped precipitously after he came to San Francisco. In August, which was generally a pretty good month for Leake, batters slugged .441 against, his sinker, which essentially was Troy Tulowitzki's slugging percentage for the year. In September, which was not generally a pretty good month for Leake, batters slugged .638, which was just a couple points behind Bryce Harper's slugging percentage for the year. When the entire league spends a month slugging like the no-doubt MVP against your fastball, that's gonna lead to some bad outcomes.

As for the drop in strikeouts (LITERALLY KIRK RUETER), that's related both to pitch selection and to pitch effectiveness. After coming to the Giants, Leake started throwing his cutter a whole lot more, upping his usage of it by about ten percent. Leake's cutter isn't really a swing-and-miss pitch; instead, it's designed to get grounders. And it was legitimately his best pitch after coming over, so it seems pretty likely that the Giants staff wanted him to emphasize his cutter, which he did, but at the expense of his sinker. They were right to see something in the cutter. Unfortunately, everything else he threw got worse.

Leake's slider was a good pitch in Cincinnati, and it stayed a good pitch in San Francisco, but its effectiveness dropped a little. He used it a little bit less, and it got hit a little bit more, but batters swung through it pretty often, so it did its job. His curve went from being a pretty good pitch to a decidedly average one, and his change-up, though it was rarely used, was a disaster. Batters slugged over 1.000 against Leake's change while he was with the Giants, which, and I've doubled checked this with the smartest statheads in the land, is bad.

After Leake came over, his stock fell real far, real fast. On August 22, I tweeted this:

If you were in charge of the Giants, and Mike Leake's agent approached you right now and said "5 yr, $90M extension" would you do it?

— groug (@moonwalkmcfly) August 22, 2015

And people universally answered yes, with the exception of one person who said he would go to $75M and not a dollar more. It's safe to say that not a lot of people around here would be too excited by that contract now. And the Giants are taking their time with him too:

#sfgiants and Leake still have not discussed a contract, I’m told, so he’ll likely test the market.

— Henry Schulman (@hankschulman) November 3, 2015

They still might try to re-sign him. He spent a couple months being pretty bad, but he has a whole career of sample size before that to draw on, and that shouldn't be thrown out. A good way to think about him is to remember Randy Winn. After Winn came over from Seattle in 2005, he tore the cover off the ball. He had a 173 OPS+ over the last couple months of that season. Nobody expected him to do that again. It was clearly a fluke, and while it was part of his skill level, it wasn't the most important part. If you'd expected Randy Winn to be an All-Star based on those two months, then you were being silly.

It's the same thing with Leake. He's a decent pitcher. He's not a bad guy to have on a team. His results with the Reds are almost certainly closer to his true talent level than his results with the Giants, so if they re-sign him, it won't be a disaster. However, the coaching staff and Leake need to be able to work together to iron out everything that went wrong for him here. If they can't, or they don't know how, then everyone would be better off if he went somewhere else.