The Astros at Memorial Day. Theme #5. The Rotation Hanging on by a Thread
Due to injuries to Arrighetti, Wesneski, and Blanco, the Astros have relied on rookie in the rotation. I examine how the rookie starters have done and why their tenure in the rotation will continue.
After a 2024 season marked by a 40-man roster that had just 5 healthy starters throughout most of the summer, the 2025 Astros entered the season with improved pitching depth.
The Astros acquired swingman Hayden Wesneski as part of the Kyle Tucker trade, and he could fill in the rotation while Lance McCullers built up to return to the rotation. They would join 4 rotation mainstays from the 2024 team—Framber Valdez, Hunter Brown, Ronel Blanco, and Spencer Arrighetti.
Through just over one-third of the season, the Astros rotation is a reminder that the best laid plans of mice, men, and front offices go oft awry. Which is a fancy literary expression for “pitchers break.”
As is the case for many pitchers, what broke for the Astros staff was their elbow ligaments. On May 18, the Astros announced the Wesneski would need Tommy John surgery to repair his UCL and would be out until sometime in the 2026 season. Ten days later, there was a similar announcement for Ronel Blanco, who will also not pitch for the rest of 2025.
Spencer Arrighetti’s ligaments have stayed intact. It’s his bones that broke, as Arrighetti broke a finger in a freak accident during batting practice in an early season series in Seattle.
Relying on Rookie Starters
With 3 of the 6 pitchers projected in the April rotation out with long-term injuries, the Astros have had to turn to 4 different rookies to join their starting rotation.
The Astros have now given 13 of their 58 starts to Ryan Gusto, Colton Gordon, AJ Blubaugh, and Brandon Walter. That’s 22%. Three of these four made their major league debuts this season and none had made a major league start previously.
The results have been about what you would expect for a set of unranked prospects who in the ideal world would be plying their trade in the Pacific Coast League. In these 13 starts, these four starters have a combined 0.6 Wins Above Replacement. That means they have done better than replacement level, but below what an average major leaguer would do.
You can see further evidence for their above-disaster-but-below average performance in the table below. It shows the stats compiled by the Astros 4 rookie starters in the middle column and those of the average MLB starter in the right-hand column.
Astros rookie starters have a 5.28 ERA in their 58 innings on the mound, much higher than the 3.99 ERA of the average MLB starter. The FIP number tells you what the ERA should be and indicates that some of that discrepancy is bad fortune—more balls are falling in against these pitchers than the average MLB pitcher. Broadly, that’s not good.
Better news is provided in the strikeout and walk numbers. The collection of Gusto, Gordon, Blubaugh, and Walter are striking out more batters than the average MLB starter and walking fewer. That’s the good news.
The bad news is that they are giving up more home runs than the average starter. A lot more. The 4 Astros rookie starters are giving up 1.71 home runs per nine innings, much higher than the average starter (1.17).
We saw this in practice in Saturday’s start by Colton Gordon. Gordon struck out 6 of the 21 batters he faced (28.5%) and allowed only an intentional walk (4.8%). But he took the loss because he gave up 2 homers over 5 innings on the mound (3.6 HR/9). It was a microcosm of the pitching style of the Astros rookie hurlers.
The injury news to Blanco, Wesneski, and Arrighetti means that the Astros are going to have to rely on Gordon and Gusto for now in the rotation. Blubaugh and Walter are in Sugar Land and may be called up at any moment to address another injury.
The Astros have little choice right now but to rely on these rookies. Arrighetti has just begun playing catch and is not likely to return to the rotation until July. Luis Garcia is expected to return this season from his own Tommy John surgery, but Dana Brown said this week he is not expected to return until “late July or early August.” While “it is clear rotation help must be one of Brown’s priorities at the trade deadline,” as Chandler Rome wrote this week at The Athletic, it is difficult to pull off a trade well before the deadline itself—which is July 31.
The Astros will have to rely on their rookies for a while. And rely on their ability and work ethic to improve, along with intelligence and savvy of pitching coaches Josh Miller and Bill Murphy.
Strong Top of the Rotation
The story of the Astros rotation in 2025 is not all a tale of injury and woe. The top of the rotation remains excellent, which we saw on Friday when Framber Valdez authored a Maddux—navigating 9 innings in just 83 pitches. The 9 innings allowed Valdez to take over the AL lead in innings pitched.
Hunter Brown has transformed himself into an ace. Brown has a 2.00 ERA this season, striking out 79 and walking only 16 in 67.2 innings on the mound this year. His 7 pitching victories leads the American League.
The aces give the Astros two pitchers in the top 11 in the American League in bWAR. The top of the rotation is strong. That’s the good news and it’s quite good.
McCullers is Pivotal
McCullers has struggled in his return to the mound after two seasons on the IL, but he seems to have made steady progress in throwing more innings and harnessing his control. The shown earlier this week when he struck out 12 and walked only 1 in going 6 innings. That it was against the A’s lineup tempers that optimism a bit.
The injuries to the rotation have made McCullers a more pivotal member of the rotation. He needs to give the Astros some effective innings since it is harder to rely on the rookies to do so.
That McCullers is a pivotal member of the rotation instead of lagniappe is an indication of the impact of the injuries to Arrighetti, Blanco, and Wesneski. It has compelled the Astros to go into their depth options for the rotation.
The results so far have been about as expected. The Astros rookies have been cromulent in the rotation. It would be better if they could rely on more proven options, but of course, Blanco and Arrighetti were not proven options when they were called on last year to serve as depth options in the rotation. Much as they stepped up—and Arrighetti improved over the course of the 2024 season—so too will Gusto and Gordon need to do in 2025.
One obvious conclusion here is that humans are not designed to throw a ton of baseballs over a relatively short period of time. Which is a fancy way to say pitching injuries are inevitable. And of course, they suck hard when they do happen, which is quite frequently. The Astros situation is also not that different than a lot of teams in major league baseball, as arm injuries are frequent and depth options are needed in just about every MLB team’s rotation.
Regardless of how common pitching injuries are, the reality of these injuries are affecting the Astros rotation greatly. The result is that the Astros will have to rely on second choice options as starting pitchers. They don’t have a choice right now.
Not to be a nitpicker, but doesn’t a Maddux have to be a shutout as well?