In the lab: Starting Pitcher BPO

Look around the Astros fansphere and you will see no other topic of conversation that has resonated as much as the conversation over the starting rotation. I pointed out earlier in a separate commentary that the Astros seem to be more focused on pitching than hitting as an organization. That is their default setting. It just so happens to be a major emphasis this offseason. This is particularly true given the fact that the Astros are set to lose arguably their best starting pitcher for the last five years.

We will exclude Framber Valdez from the equation because he is unlikely to come back. So, we are looking at two different buckets. We are looking at qualified starters and unqualified starters. The idea behind bases per out was that it could be a way to evaluate hitters and pitchers. We take total bases, walks, stolen bases, and hit by pitches and divide it by the total number of outs. We saw that the median for position players was .678, so the median for pitchers should be similar. However, in order to have a limit on sample size, we looked at only starters with ten or more starts. That ended up being 182 starters. As you will see, the list of qualified starters will be alarmingly short. We will include their ranking and the BPO+ amongst starters. The starter median was .665. All BPO+ scores over 100 are better than average. All BPO+ scores below 100 or worse than average

Qualified Starters

Hunter Brown

• BPO: .529
• Rank: 16th out of 182
• BPO+: 12o

I simply detest the term “ace”. It is a mythical term that changes depending on the person. Brown finished in the top three in Cy Young voting, so he would seem to qualify as a number one pitcher. If each team employs five pitchers and there are 30 teams, we are looking at the top 150 starting pitchers. The others are fill ins or swing guys that will make spot starts when the need arises. So, if we divide 150 by five then we are looking at the top 30 starters as number one type starters. Brown fits that bill. The question on him long-term will be how long he will stick with the Astros. After Jeremy Pena, he seems to be destined to be the next big guy to eventually leave town. A repeat of 2025 would give Brown all the leverage he would need in negotiations.

Mike Burrows

• BPO: .646
• Rank: 78th out of 182
• BPO+: 103

In the grand scheme of things, the Burrows acquisition was huge for the Astros. He will not be Framber Valdez, but based on the numbers from last season he will be a number three starter type. He had former Astros pitching coach Brent Strom as his pitching coach in Pittsburgh, so I’m not quite sure how much improvement we can expect in the Astros pitching lab. There is talk of adding a two seam fastball to his arsenal. I warned against “magical thinking” in my commentary piece and we definitely want to avoid it in this lab. So, we need to keep our expectations reasonable and assume he will pitch somewhere in the neighborhood of 150 innings at around the same rate as last season. So, we are still looking for that mythical number two starter.

Jason Alexander

• BPO: .764
• Rank: 148 out of 182
• BPO+: 85

To be perfectly fair, Alexander had a .687 BPO as an Astro last season. He pitched all of six innings as a member of the Athletics and had an 18.00 ERA in those six innings. As a statistician, I would call that noise. As a fan, I would chalk it up to the Astros magic of converting pitchers into usable players. However, we have to be careful with how we define usable. If we simply go with the overall results then Alexander (AKA George Costanza) barely qualifies as a top five starter. I certainly won’t speak for the Astros here, but I am sure the internal conversations involve them hoping he does not wind up as one of the top five starters when the season opens.

Colton Gordon

• BPO: .833
• Rank: 172 out of 182
• BPO+: 75

Gordon was 6-4 on the season with 14 starts. Those marks (along with his 5.34 ERA) are a testament to patchwork that these pitching coaches pulled off all while explaining a part of the reason why the Astros came one game short of getting to the playoffs. Gordon is a nice guy to stash in Sugar Land, but he is definitely a “break glass if…” kind of proposition.

Lance McCullers

• BPO: .964
• Rank: 180 out of 182
• BPO+: 55

McCullers is here because he signed probably the worst contract extension in Astros history. It technically started in 2022 and ends this season. At 17 million per season, it wasn’t big enough to cripple them, but shoot Dana Brown with truth serum and he would tell us that 17 million dollars would have gone a long way in making this offseason easier for him and the Astros.

Unqualified Starters

Cristian Javier

• BPO: .649
• Rank: 81 out of 182*
• BPO+: 102

The asterisk denotes that Javier did not qualify for the ranking officially because he made only eight starts. Javier is a Rorschach test of sorts. He has not been healthy since the 2022 World Series season and missed virtually all of 2024 with TJ surgery. He came back late in 2025 and looked ordinary at times and spectacular in others. The kids call it wishcasting, but a certain optimistic point of view would indicate he will be stronger and better in his second season after TJ surgery. The pessimistic view is that he is injury prone and cannot be counted on. The spot in between is that he will be a league average pitcher. That’s nice if you are looking for a number three or four starter. It’s not promising if he is penciled in as your number two.

Ryan Weiss

• Won-Loss: 16-5
• Innings: 178.2
• ERA/FIP/xFIP: 2.87/3.23/.3.28

Unfortunately, the data needed to compute BPO was not available via fangraphs or baseball-reference because they did not report total bases or even doubles, triples, and home runs so that total bases could be computed by hand. Most analysts view KBO as a AAA equivalent league. So, how would we feel if we saw these numbers in Sugar Land? If you include over 200 strikeouts you’d probably feel somewhat optimistic, but again we should not be in the business of forecasting in the lab. If he turned in an ERA between 4,00 and 4.50 I think the Astros would be pleased and would gladly take that from a fifth starter.

Nate Pearson

• Career BPO: .781
• Rank: 157 out of 182*
• BPO+: 83

I should note that this comes in over 150 career innings with six starts. So, he has mostly pitched out of the bullpen. He was actually good in only 19 games in Chicago in 2024, but the rest of the time it has been rough. He would seem to be similar to Jason Alexander in quality, but he offers more upside with his stuff. He would appear to be on the Costanza, Gordon, and Brandon Walters track. He is a nice arm to have when you need it, but if he is in the rotation on day one it will either be because the Astros pitching coaches have practiced some witchcraft or some other arms never materialized.

A.J. Blubaugh

• BPO: .531
• Rank: 17 out of 182*
• BPO+: 120

Let’s stick with the Hunter Brown comparisons for now (since he ranks right after him in a would be BPO ranking). Brown had a similar auspicious start in 2022 when he was 2-0, with an 0.89 ERA in just 20 innings. He didn’t really become Hunter Brown until 2024. That 2023 year was a growth season that saw him pitch 155 innings with a 5.09 ERA. He had a .756 BPO that season. I’m not necessarily predicting the same for Blubaugh, but I think it is instructive that we should avoid getting too excited over limited results in 2025. The hope is that he could either get to 150 innings and be around league average or be considerably better as a 7th inning guy out of the pen.

Spencer Arrighetti

• Career BPO: .762
• Rank: 146 out 182*
• BPO+: 85

Arrighetti is another Astros fans Rorschach test. If you look at the raw numbers you see an end of the rotation starter. However, he had a significant stretch in 2024 where he was much better than that. He had a .741 BPO that season, so even in that year he was not good overall. Were those just growing pains or is this the pitcher that Arrighetti is? The answer is probably somewhere in between. If I were a betting man (I’m not), I would set the over/under at .700 for his BPO. If he reaches that mark he would be a solid fourth starter and the Astros would probably be happy. That’s of course if he is healthy enough to do so.

The Unmentionables

I did not mention Hayden Wesneski, Ronel Blanco, and Brandon Walter because they likely won’t be available until August at the earliest. However, they will factor into the conversation at some point. We know one of the reasons why Dana Brown did not pull the trigger on a pitcher deal at the deadline is because he thought that the combination of Luis Garcia, Javier, and Arrighetti would get him through the end of the season. Only Javier lasted through the end. So, they sit in the background as possibilities. They are lottery tickets as far as 2026 is concerned, but will factor into the long range plans of the organization.