Zack Godley Made a Change and it Appears to be Working

Zack Godley has had a rough year. There have been many, many calls to move him to the bullpen after his rough start to the season. His velocity is down from last year. He’s looked really wild at times and was roughed up hard by the Brewers and Giants.

Yet, he’s slowly but surely started to turn things around. I am generally not a big advocate of taking small(ish) samples and breaking down into smaller samples but sometimes this can be warranted if you can tie it to a meaningful change.

Can we do that with Godley? Let’s find out.

I’m going to set a before/after date of the June 10th start at Colorado. (Incidentally, you may recall I noted a mechanical change for Patrick Corbin last year on June 8th and it not only continued through all of last year, but he took another step forward this year)

These are pretty big improvements across the board. Notable, his ERA is down more than a full run and his FIP is down 1.69 runs. I added his BABIP to show that some of ERA difference from his FIP has been from some bad luck on the batted balls (in his last 8 games, his ISO allowed is .110, which is fantastic; he has been beaten up by singles in bunches) though part of this is also due to his penchant of walking players in bunches.

But the big kicker here is that he has substantially improved his K% (and validated with the massive uptick in SwStr%) while roughly maintaining his BB% and significantly decreasing his homer rate.

So what can we find? First, let’s look at pitch usage.

I added a red square around the June 10th before/after date to make it easier to see the trends before and after. I did this for all of the following charts.

This does give us some really meaningful data - after June 10th, Godley started throwing more curveballs and to great extent. And he compensated with less sinkers. More of his best pitch and less of his worst pitch (ignoring the changeup). This makes a lot of sense and is essentially what Corbin did for his “breakout” last year and moreso this year.

But it goes further. So if he’s throwing more curveballs, is he still getting whiffs with them?

Another sign of improvement! A gradual increase in the whiff percentage on his curveballs.

So Godley not only threw more of his best strikeout pitch, but he also got better results on them! To me, this is a huge sign that a mechanical change was made or else batters would simply adjust.

After some digging, it becomes quite obvious what that change was:

Here it is! An adjustment! This is a literally physical thing that Godley is doing different over the course of the season and we can quantify it! What this chart is telling you is where Godley is standing on the rubber when he releases the pitch. He has moved about 4-6” to the left (towards LHB) since the start of the season.

And you can see that he was gradually making these changes in May (notice the four straight starts going up starting with “ARI@LAN (5/18)), then he had that disaster of a game in Milwaukee and reverted back to where he started the season for the Cincinnati game. But after reverting back, he was shelled even harder in San Francisco and went BACK to the change he was making and has been there since.

Baseball is a wonderful game!

Let’s keep digging. Have these curveballs moved in location as they cross the plate?

There isn’t really much of a change in where the pitch is crossing the plate. So what this means is that Godley was aiming for the same target (low and off the plate to right handed hitters) but moved his starting location about 6” closer to that target. Keep in mind that all of his pitches have “straightened out” like this, not just his curveball.

What does this mean? It means he was throwing less “across his body” and throwing his pitches straighter to the plate. To help demonstrate, I mocked up a quick diagram in MS Paint:

Now, this picture has been exaggerated to help illustrate the point, but essentially, the red line is where he was throwing his pitches and the blue line is where has has moved to. Hopefully you can see that the new location is “straighter” to its intended target. These kind of things generally help to reduce platoon splits (which is the same rationale why sidearmers generally have much bigger platoon splits compared to over-the-top pitchers) but it can also help with command.

For Godley, I think it’s mostly helped with his command. His wOBA against left handed hitters has only dropped from .345 (before June 10th) to .333 (June 10th - present). However, his pitch command has vastly improved:

On the left is the before picture and on the right is the after picture. And you can see a clear theme: he has done a better job of getting his curveballs off the plate and down. And while the chart above shows that the “average” location hasn’t changed too much, this change shows his overall “spread” has been smaller, e.g. he’s been more consistent in where he throws it.

This supports a lot of what I saw from Godley early in the season - he still had that strikeout stuff but he was often overthrowing or missing his targets wildly. Maybe this was all he needed to regain some of his control or maybe there is more to it. But this is a very real adjustment that Godley has made and it has had very real results from it. For me, my vote is to keep Godley in the rotation, at least for now.