The Launch Angle

The Piracy Project

When the Astros acquired Mike Burrows in December, there was a fair amount of optimism among Astros fans, we here at The Launch Angle included. After all, we’ve seen this story before. Acquire a former Pirate, bring him to the Astros’ pitching lab, come out with Charlie Morton, World Series Game 7 winning pitcher. Acquire another Pirate, bring him to the Astros’ pitching lab, come out with Gerrit Cole, Cy Young finalist.

With the Astros needing to shore up their starting pitching in the offseason, why not go back to that well, even if it costs a top prospect in Jacob Melton? Astros fans could hardly wait to see how Burrows would transform once pitching coach Josh Miller got his hands on him.

Astro Mike vs. Pirate Mike

Two months into the season, any transformation has been difficult to see. On the plus side, he’s been healthy all season. That is no small achievement for the 2026 Astros; Burrows is the only member of the opening day starting rotation who hasn’t gone to the IL. He’s made every start like clockwork, but it only amounted to a 3-6 record in 11 starts with a 5.40 ERA. Comparing 2025 Pirate Burrows to 2026 Astro Burrows, most of his numbers have gone in the wrong direction.

The ERA is up, the FIP, xFIP and SIERA are up. The WHIP is up. Strikeouts are down, swings and misses are down, and the walk rate hasn’t really changed.

In fairness, Burrows has had a higher BABIP this season, and some of his advanced metrics suggest he’s been about the same. His xBA and xwOBA aren’t any different than last year. Neither is his xERA, which is actually a touch better.

Comparing his sliders from 2025 to 2026, there’s actually not a lot of difference. Some of the percentiles moved up or down some, but the absolute values for a lot of those metrics are still pretty similar. The middle of the bell curve for a lot of these metrics is so crowded that minor absolute value increases and decreases can result in relatively larger percentile changes. Just like his xStats, stuff like Fastball Velo, GB%, Chase %, Barrel %, Hard Hit % and Avg Exit Velo are about the same, or again, in some cases, a touch better.

“No different” or “a touch better” is disappointing, though, for a team that found new levels of dominance for guys like Morton, Cole, Justin Verlander and Ryan Pressly.

Did the Astros change anything with Burrows? Why haven’t we seen that large step of improvement we’ve come to expect?

Two Halves of Mike Burrows

Here’s a comparison of his pitches in 2026 compared to last year:

None of his pitches’ speeds are all that different, and he’s still utilizing his same five pitches: 4-seamer, Changeup, Slider, Curveball, Sinker. The distribution of pitch selection is a little different though.

When you look at the breakdown of pitches against righties and lefties though, you can see that the change in his pitching approach is much more dramatic against righties.

Against lefties, Burrows is throwing his 4-seamer a little less, but the distribution of pitches is still relatively the same as last year.

Against righties, Burrows now throws his 4-seamer almost half as much, and utilizes his sinker almost 3 times as much. The curveball also comes into play more, and he’s dialed back on his slider usage a little bit towards righties.

These changes have improved his numbers against right- handed hitters significantly.

Across the board, by almost every metric, xBA, xOPS, xwOBA, Whiff%, right-handed hitters are not hitting Burrows as well as they were before. This seems like a win for the Astros’ pitching lab.

Unfortunately, this improvement is canceled out by his putrid performance against left-handed hitters.

Again, across the board, by almost every metric, xBA, xOPS, xwOBA, Whiff%, left-handed hitters are now just crushing Burrows. Astros pitchers struggling against left-handed batters has been a season-long problem.

So it’s not really that Mike Burrows hasn’t improved. It’s that 2026 Mike Burrow is comprised of two halves: the half that pitches to right-handed batters, which has improved a lot, and the half that pitches to left-handed batters, which has gotten a lot worse.

One step forward, one step back. Maybe even one and a half steps back.

If the pitch velocities didn’t really change, and his pitch selection and distribution to lefties didn’t really change, then why did his results change so markedly?

You may have noticed on the graphic comparing Burrows’ 2025 and 2026 Pitch Movement profiles a rather large change in the lower right hand corners: his arm slot angle.

Since becoming a Houston Astro, Burrows’ has dropped his arm angle a whopping 9 degrees, from 48 degrees to 39 degrees. Burrows had dropped it a little from 50 to 48 degrees from 2024 to 2025, but a 9 degree change in mechanics is substantial from one year to the next.

You might drop your arm angle some to decrease your vertical approach angle (VAA) so that your fastball doesn’t seem to drop as much, making it seem like it rises. I don’t think Burrows is really getting a lot of that effect. His vertical movement is about the same as last years, actually 1″ more.

From a platoon perspective, the arm slot angle change might explain some of the changes in Burrows’ results to both right-handed and left-handed hitters.

A right-handed pitcher dropping their arm angle would increase their advantage against righty hitters, as righty hitter would have a tougher time picking up on the pitches. Lefty batters, on the other hand, would get a clearer sightline on pitches. And so far this is exactly what has happened in 2026. Burrows has gotten better against righties and worse against lefties.

We see this with other pitchers too, like Spencer Arrighetti. Arrighetti’s 19 degree arm slot angle is the 3rd lowest among MLB starting pitchers. He has done very well against righties, but routinely grades poorly against lefties.

Burrows is under team control through the 2031 season, so there’s a lot of time left to get value from his appreciable potential, but there’s still a good amount of tinkering left to do.

Pirates @ Astros Game Information and Gamethread Details

Bubba Chandler will take the mound for the Pirates opposite Burrows. Chandler, a rookie RHP, is 1-6 on the season through 11 starts, with a 4.85 ERA over 52 innings. He has a blazing fastball that average 98.5 mph and a 9.0 K/9 rate. If you’re wondering if this could be Misiorowski all over again, Chandler isn’t quite there yet with his control, as he has a whopping 6.2 BB/9 rate this year.

Also, no, his real name is not Bubba. It’s Roy, and right now Roy is the only active Bubba in the majors. Prior to him, Bubba Thompson played outfield for the Rangers and Red from 2022-2024.

This post will be updated with starting lineups as they are made available.

The game will be broadcast at 7:10 p.m. CT on SCHN with radio coverage on KBME 790 AM.

We hope you will join us and the rest of the Launch Angle community for the game! The turnout has been amazing on the TLA Discord Server for the game threads. It’s been a blast as the Astros seem to be finding their footing on the season.

Join us again for today’s game. Just join the Discord server using this link: https://launch-angle.com/discord .

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Feature photo from  @astros on X,  Source Link (cropped).