Even just a couple months ago, Justin Verlander was a name. He was a name with a contract and diminished results, and his desirability on the market was low. Teams were interested in him, for sure — teams would always be interested in someone with Verlander’s background. Yet his performance wasn’t matching up with his cost, and so it didn’t seem like a trade would be likely. The Tigers didn’t want to give their legend away, yet contenders didn’t want to pay for someone whose best days were long gone.

Ultimately, Verlander did get traded. The Tigers, admittedly, paid him down, but the Astros picked up the bulk of the money, and they even gave up three legitimate prospects. The Astros paid for Verlander as if Verlander were an ace again. And for the past several weeks, Verlander has resembled an ace. He made his debut for Houston on Tuesday, and he allowed one run over six innings. Verlander’s gotten back to looking like one of the best in the world. So, what changed? What convinced the Astros to pay what they did? Outside of their own pitching issues, I mean. Verlander, it won’t surprise you, has made a couple tweaks.

To revisit a point from before: It was never going to take that long for a contending team to buy into a hypothetical Verlander turnaround. His track record speaks for itself, and even while Verlander was having a rough go of it, his stuff was all there. He wasn’t pairing increased walks with a decreased ability to throw 95. Verlander’s thrown hard all season, and he definitely had it going Tuesday night.

So it stood to reason that a healthy Verlander might eventually be able to find his level. He seems to have found it, being particularly experienced in the art of making adjustments. Verlander has bounced back from ineffectiveness before, and for this specific case, there are two things I’d like to highlight. First, we can attempt a general examination of his mechanics. Mechanics are complicated, and pitchers can make tweaks you can’t even spot with the naked eye, but here, let’s think about the difference between actual velocity and what Baseball Savant calls “effective velocity.” Actual velocity is obvious. It’s how hard a pitcher throws a pitch. Effective velocity, though, considers extension, and total flight time. The closer to the plate a pitch is released, the less time a hitter has to react.

Verlander has never been some kind of forward-extension dynamo. He’s not Carter Capps. In 2015, his average pitch “seemed” 0.6 miles per hour slower than it was. Last year, his average pitch seemed 0.7 miles per hour slower than it was. That’s all well and good, but it doesn’t say much. Here now is Verlander’s 2017 season, on a start-by-start basis.

It’s not the easiest thing to interpret, because we don’t attempt this sort of analysis very often, but you can observe a general trend line. The trend line is up, positive, away from more strongly negative figures. Verlander lately has gotten more extension than he did earlier on, and what this suggests to me is cleaner mechanics, mechanics where Verlander doesn’t cut himself off. He’s looking more like he used to, at least in this regard, and old familiar Verlander is a good version of Verlander to mimic. Something here seems to have been straightened out.

And then there’s another thing. Verlander, on the fly, has changed what he’s been throwing. It’s been subtle, but you can see it in this comparison of Verlander’s fastball and slider velocities, by game.

As the fastball has stayed fast, Verlander has taken something off of his slider. It happened a few starts into July, which you can see in the following table.

Justin Verlander Sliders Split Usage Velocity H Mov V Mov Strike% Contact% K% Through 7/8 19% 90.0 -0.1 4.9 64% 76% 22% Since 7/14 24% 87.3 1.1 2.6 68% 61% 40% SOURCE: Brooks Baseball

Over the past couple months, Verlander has bumped up his slider usage, while reducing its average speed by almost three ticks. Movement-wise, the biggest change is that the more recent slider has more than two extra inches of drop. The recent slider has been thrown for more strikes, and it’s also induced a far greater rate of swings and misses. The last column might trip you up. Through July 8, Verlander got 22% of his strikeouts with the slider. Since July 14, that rate has nearly doubled. Verlander has leaned on the slider more, and, combined with the four-seamer, Verlander has looked more like almost a two-pitch pitcher.

He does still have a curveball. It hasn’t gone away. The changeup has. Verlander hardly ever throws that anymore, even though it used to be one of his very best pitches. Sometimes, pitches just come and go. The Verlander of right now goes fastball — slider — curve. It’s been paying off in a fairly major way.

One of the most interesting aspects about this slider change is that it’s effectively undone a change he made previously. Verlander didn’t tweak to a new slider; he went back to an old slider.

A season ago, the hard slider was more of a new thing, a new wrinkle, and it was fantastic. By pitch value, the slider was 2016 Justin Verlander’s most valuable weapon. With that in mind, I don’t really know what to tell you. Verlander developed a thing that worked last summer. This year, it stopped working so well, and so Verlander has reverted back to an old motion and grip. He at least had history to fall back on, and Verlander’s settled into a heck of a run. Maybe, in time, the hard slider will reemerge. Maybe the old slider is back to stay. Verlander has demonstrated his capacity to adapt, trying as best he can to remain a half-step ahead. He won’t always be where he wants, but, generally speaking, you could say that Justin Verlander deserves the benefit of the doubt.

The pitcher that exists today has a familiar-looking slider and the same old overpowering fastball. The changeup is gone and the curve is in the back pocket, but the two primary pitches have been effective, in part probably because of whatever Verlander got mechanically polished. Everything — everything — always has to work together. Verlander has it all working, and because of his rapid turnaround, he’s in position now to pitch a team to the World Series. Everyone, in some way, has gotten their wish.