The On-the-Fly Reinvention of James Shields

James Shields is the oldest part of a young and rebuilding White Sox ballclub. For that reason, he’s easy to overlook. Even fans of the team itself would presumably rather focus on, say, Yoan Moncada or Lucas Giolito or Reynaldo Lopez. Those guys, and others — they could be around the next time the White Sox make the playoffs. Shields, almost certainly not. He might not even still be in the game.

So this isn’t a tale with widespread implications. This isn’t a story that’s going to change how you think about the broader baseball landscape. All this is is a story of a pitcher who’s come back from the brink of professional extinction. James Shields will turn 36 a few days before Christmas, yet over the last couple months, he’s changed the way that he pitches. Shields still has something left to give after all; all he had to do was alter everything, at a time when it would’ve been easy to wave the white flag.

Five years ago, the Royals thought enough of Shields to swing a blockbuster trade that remains fiercely debated today. Five years is not very much time. Five years is also a baseball eternity. More recently, Shields turned into a pitching disaster. There’s really no other way to put it. He started to struggle with the Padres, then he got even worse with the White Sox. From 2016 through the first four months of 2017, there were 175 starters who threw at least 100 innings. Shields allowed the second-highest wOBA. He allowed the fifth-highest ERA, the highest FIP, and the third-highest xFIP. With no exaggeration, Shields was about as bad as Jered Weaver. When he was discussed, it was only as an opportunity to bring up Fernando Tatis Jr. Oh, how the White Sox would regret it.

The White Sox, I’m sure, do regret it. Given their organizational direction, they’d love to have Tatis Jr. back. But Shields flipped a switch. Shields has shifted his own trajectory, and to explain how, consider a start he made in Boston on August 5. Here is the first pitch he threw.

Here now is the last pitch he threw.

Look closely. Look at Shields upon release.

Somewhere in the middle of the game, James Shields dropped down. His release point shifted down, and more toward third base. And this wasn’t just Shields toying around; this wasn’t a one-off, a quick different look, like we’ve seen from, say, Clayton Kershaw. Here’s a comparison of Shields against the Blue Jays on July 31, and Shields against the Angels on September 25.

James Shields had one way of throwing. More and more often, his pitches were getting pounded. And so, early this past August, Shields lowered his arm slot on the fly. Not just once, not just twice. Permanently. Shields made a significant mechanical tweak, and he’s stuck with it ever since.

You can see how things have changed in this plot of vertical release points, from Brooks Baseball.

The shift in that game-by-game 2017 plot is unmistakable. Sometimes, when you see an arm slot drop, you’re inclined to think the pitcher might be hurt. This isn’t about an injury — this is intentional. Shields, in the past, has tried to downplay what he’s been up to.

“All it is now is I am back to a three-quarter guy,” Shields said of his new approach. “I used to be that way, but a few years ago I started to throw over the top. I just have gone back to it. I feel comfortable with it. We are just going to go the rest of the season with (the three-quarter arm slot) and see how it goes.”

That doesn’t seem entirely truthful. Obviously, Shields knows his own mechanics far better than I do, but what he says doesn’t match the data. According to said data, Shields is different now from how he was before throughout the entire decade.

This is something that, to our knowledge, Shields hasn’t been. On certain occasions, we see arm slots get reworked during the winter. Far less often do we see a change like this as a season is actively going on. It’s difficult to work on mechanics on the fly, because when you’re involved in regular-season game action, the stakes are high, and your body wants to revert to the familiar muscle memory. Shields has worked to overcome that. Here’s a plot of 2017 vertical release points, splitting the year at August 5. The Shields point is highlighted in yellow. He’s a clear outlier. Release points are consistent, unless there’s a major change.

The low arm slot isn’t completely new. Shields has apparently screwed around with it for 10 years. Just, not in games. His own teammates seem to have encouraged him to try this experiment. He’s made a full commitment to it, in a way that isn’t the case when a pitcher busts out some new breaking ball or knuckler. This isn’t just about a random different look. You throw differently when you throw differently. I know that seems tautological, but Shields changed his familiar mechanics, for every pitch. When you change your arm slot, you change every one of your pitches. The pitches move differently, because they’re coming from different places, and that means the pitches work differently together. It’s a risky thing to attempt, because in a few senses, Shields is now just a different pitcher. But he didn’t have much to lose. He was already getting plastered. And the turnaround has been dramatic.

The last column shows that Shields’ vertical release point has dropped more than nine inches. His horizontal release point has also moved about a foot, toward third. You have to figure that has a lot to do with the changes in the other columns. Shields’ K-BB% has doubled. His strike rate is up, and his contact rate is down. Shields, lately, hasn’t been a great starting pitcher, but he’s been a fine starting pitcher, an average starting pitcher, where he used to be awful. He had been pitching himself almost out of a job. Then came the change, then came the sudden improvement. The White Sox now should feel better about still having Shields under contract for 2018.

Not that Shields has committed to keeping this up in 2018. That’s all still to be evaluated, over the next several weeks. But I don’t know how Shields could let this go, after the run that he’s been on. He should at least give this delivery an opportunity to fail. The old way was already failing. Maybe this is somehow rougher on his body, I don’t know, but even in that case, maybe it just takes getting used to. One version of James Shields has been useful over the past two seasons. It’s been the version that’s dropped its arm down.

Said the reigning league MVP, after Shields’ game Monday:

“That was definitely a different Shields,” Angels outfielder Mike Trout said. “He was moving the ball around tonight.”

The second half of that means nothing. The first half of that means everything. I don’t know how important James Shields’ career is to the White Sox these days, but I’m sure it’s important to James Shields. That very career might still be far from over. Shields’ delivery has breathed into it new life.