Certain guys, people just assume are going to get injured. For as little as we actually understand about pitching mechanics and injury risk, there are certain players who look like ticking time bombs. Chris Sale is considered one of those guys, and this is why:

Basically that simple. Sale is (1) a pitcher who (2) looks like that when he’s pitching. And Sale, sure enough, has had his injury scares. Earlier this very season, he was on the disabled list. But, a few years ago, Sale threw 192 innings. Last year he reached 214, and he still hasn’t had the disaster scenario. Sale’s kept himself healthy enough, and he’s recently made a change to try to keep it that way.

Thursday, Sale pitched against the Tigers, picking up a loss despite a winning effort. Three times, Sale had to go through Miguel Cabrera. Previously, when Sale and Cabrera matched up, Sale threw sliders a quarter of the time. But in the first inning, he threw Cabrera six fastballs and a changeup. In the fourth, he threw four fastballs and two changeups. In the sixth, he threw five fastballs. So, out of 18 pitches to maybe the best hitter in baseball, Sale didn’t throw a single slider, as he had often in the past. And to go beyond Cabrera, Sale struck out the side in the third on 13 pitches, and all three strikeouts came on changeups. It’s not a coincidence.

This is Chris Sale, developing. Sale has long had a changeup that was, at the very least, useful. It didn’t show up very often when he worked out of the bullpen. As a starter, for a while, Sale was fastball/slider, and the slider was plenty good enough. But not only do most starters eventually require a reliable third pitch — the slider, at least by reputation, is dangerous. Zack Greinke has talked about protecting his elbow by reducing his slider usage. Chris Sale is following suit. From an article by Dan Hayes:

Through four starts this season, Sale has relied on the changeup much more than he ever has. Part of it is longevity and keeping his arm in shape instead of relying on the slider.

For Sale, there are a few goals. One, he wants to keep himself healthy and able to pitch. Two, adding a better changeup should allow him to be effective longer within games. And three, Sale indicates that the changeup helps him keep his mechanics consistent. These things always sound good in theory, but Sale’s gone beyond theory, to the point where he’s genuinely executing. He’s dramatically cut down his slider usage. By our data, he’s increased his changeup usage by 12 percentage points, the biggest hike in baseball. According to Brooks, he’s actually second to Henderson Alvarez, but by the same source Alvarez used a changeup often in the past, so at least for Sale this is significant and new.

And Sale owns a career-high strikeout rate. He owns a career-low walk rate. Since he came off the disabled list, he’s posted a league-leading K% – BB% of 33%. Sale’s gotten better against both lefties and righties, and for an idea of the confidence he’s developed in his change, consider this 3-and-0 delivery to Cabrera from Thursday:

That’s a change that Cabrera wasn’t expecting, because you don’t expect a 3-and-0 change. It was in a good spot, it got weakly fouled off, and Sale came all the way back to whiff Cabrera two pitches later. Sale has simply swapped his preferred secondary pitch between seasons, and if we can’t prove it’s made him better, it at least hasn’t made him worse.

For another glimpse at how Sale has kind of phased the slider out, here are his rates of strikeouts for which the slider was responsible:

2012: 58% strikeouts on slider

2013: 52%

2014: 22%

Sale’s slider is still good. It’s still Chris Sale’s slider. This season it’s been knocked for all of three hits. But Sale hasn’t needed to rely on that pitch, as his changeup has been knocked for just 11 hits despite a large gain in frequency. The one Sale changeup hit for extra bases so far wasn’t even a bad changeup; it was a good changeup thrown to an amazing hitter. Otherwise, the changeup has gotten 20 strikeouts and ten singles. Righties have struck out against the changeup 17 times; they’ve struck out against the slider six times. Last season, those numbers were 34 and 79.

There’s another interesting fact — from last year, Sale hasn’t increased his fastball velocity. But his changeup is up a tick and a half, and his slider is up a couple ticks. I can’t explain that, exactly, but I felt like it belonged somewhere in here, and what it might suggest is that Sale has greater strength, and he’s just conserving his fastball heat for when he needs to still be strong later on. That’s just speculation, but clearly, Sale hasn’t just changed his mix; he’s also just throwing better.

Finally, I have one more thing to say, concerning Sale and hitters and their disrupted timing. A season ago, when hitters made contact against Sale, they fouled the ball off 47% of the time, hitting the ball fair the remaining 53% of the time. This season, Sale is at 58% fouls, which is the second-highest rate in baseball. That gain of 11 percentage points isn’t only baseball’s biggest; it’s baseball’s biggest by more than four percentage points. And, between 2012-13, this stat yielded an r value of 0.77, suggesting it reflects some ability. Sale might now be more able to induce fouls instead of balls in play, indicating a greater difficulty for hitters to square him up. More fouls can lead to more strikeouts. Fouls, after all, are strikes, and balls hit fair can go for hits. I haven’t studied foul-ball generation enough to issue strong conclusions, but it seems to me this is more a good thing than a bad thing. It’s more evidence that hitting against Chris Sale is a nightmare.

Sale, a few years ago, was worth five wins. Sale, last year, was worth five wins. Sale was already outstanding, averaging 0.17 WAR per start. This year he’s at 0.23 WAR per start, after making a change intended to both make himself better and keep himself healthy. Though he has already been sidelined, the White Sox and Sale will take the occasional brief DL stint provided there isn’t anything worse, and Sale believes he can improve his odds by regulating his slider usage. It’s good when a pitcher tries to stay healthier. When a pitcher tries to stay healthier and gets better in the process, that’s basically perfect.