Luis Castillo's struggles continued against the Brewers Sunday, as he was tagged for five runs in five innings while walking four, allowing five hits, and striking out five. That came after a somewhat promising star earlier in the week that saw him strike out 11 in five innings -- while still giving up three runs. It was a week that saw Castillo take a half-step forward and then a full step backward, leaving him about 10 steps behind where he was supposed to be coming into the season. 

Castillo is now 10 starts into the season with a 1-7 record, a 7.61 ERA, and a 1.80 WHIP. He has career-worst numbers in pretty much every category -- his walk rate is right around his career average, so he's got that going for him -- and after Sunday's start, it's hard to find much to be optimistic about. And I want to be optimistic.

After Tuesday's 11-strikeout outing, you could tell yourself Castillo was starting to figure it out. Sure, three runs in five innings isn't great, but it was really just one bad pitch that accounted for all three runs. Castillo racked up a whopping 21 swinging strikes on 91 pitches, including nine with his slider and eight with his changeup while limiting hard contact with both pitches. 

And, because of his track record, it might have been the kind of thing where Castillo could just have figured it out one day and pitched like himself the rest of the season. That's what I was hoping we were seeing Tuesday. Sunday's start is a sign that isn't happening. At least not yet.  

What's gone wrong for Castillo? I wrote last week about how his changeup hasn't been as effective this season, but it's really been the other pitches that have gotten crushed. As Justin Choi wrote about at, Castillo's changeup has looked a little different -- a bit more drop on the pitch, which he's throwing below the strike zone more often -- but the bigger issue has been how often he is throwing the rest of his pitches in the heart of the strike zone. That, combined with the added drop on the changeup, seems to have created a situation where Castillo's best pitch can't be as effective because opposing hitters may be able to see it coming better than they have in the past. 

Physically, Castillo seems fine. He's throwing about as hard as he usually does, and while there's some evidence his release point hasn't been as consistent as in years past, there isn't some big, obvious issue you can point to. He just … isn't pitching well. He looks like 90% of himself, but that 10% might be the key. 

Pitching is incredibly difficult to do, and it's incredibly difficult to predict. Partially, that is because there is inherent volatility to it -- sometimes, batted balls fall to the ground instead of ending up in a fielder's glove, or sometimes that slider you hung got thrown to the slap-hitting second baseman instead of the slugging outfielder. 

But the margins of error for pitchers themselves are also extremely slim sometimes. The difference between an effective fastball and a meatball can be a few inches or a few mph in velocity. A wipeout slider can become a liability if your grip isn't exactly perfect or your posture is just off. We see so much change from one season to the next with so many pitchers that you can't just write off that, for whatever reason, the number of small differences in Castillo's approach have turned him into one of the worst pitchers in the game. 

I'm skeptical that's the case, but I'm certainly less confident in that position than I was even a week ago. I've stubbornly refused to move Castillo outside of my top 20 at starting pitcher, because he was originally in the top-10 range, and I need a lot of evidence to change my opinion about a player that much. At this point, I can't ignore the fact that Castillo doesn't look like himself -- even though he doesn't look that much different. If there was some reason to be optimistic, I would point to it, but I don't have it. That's just where we are right now. 

Of course, the question now isn't "should he be moved down the rankings?" but, "How far does he need to be moved down?" My colleagues already have Castillo outside of the top 30, and for me, that would mean dropping him behind this group that closes out that range of my SP rankings: Jose Berrios, Ian Anderson, Pablo Lopez, Kevin Gausman, and John Means. I'm fine with that. Berrios is as solid as they come, though he doesn't have Castillo's upside; Anderson, Lopez, Gausman, and Means have all shown plenty of upside over the last two seasons, but don't have the track record in a large enough sample size for me to move them into the top 20 yet. 

What about moving him beyond that? I've got Sonny Gray, Max Fried, Dylan Bundy, Trevor Rogers, and Lance McCullers ranked 31st through 35th, followed by Shohei Ohtani, Freddy Peralta, Carlos Rodón, Tyler Mahle, and Jesus Luzardo. That's a much tougher group to figure out. There's something to really like about a lot of those pitchers, but the first five have all struggled with consistency of their own except for Rogers, who shares innings concerns of the likes of Ohtani, Peralta, and Rodón. 

Nobody in that group can really compare with Castillo's theoretical upside in 2021. Some of them could give you ace production, but none could realistically be expected to give you ace production and an ace workload. Castillo could. 

But he's pitching so much worse than them -- so much worse than every pitcher in baseball right now -- that I can't really rank pitchers with that group's potential above him. So, outside of the top 40 it is. After that, I've got a tier of guys I consider solid, reliable mid-rotation arms -- Zach Eflin, Marcus Stroman, Zach Plesac, Aaron Civale -- and then a very interesting name: Robbie Ray.

Ray is pitching incredibly well right now. That's happened before, but not this: He has one walk in six starts. A 49-to-1 strikeout-to-walk ratio, in fact. That's completely unprecedented for Ray, and it's not hard to see how it could make him a legitimate ace pitcher moving forward, even if he's had some issues keeping the ball in the yard in that stretch. 

Of course, Ray is no stranger to inconsistency, and he's coming off a 6.62 ERA in 51.2 innings in 2020 himself. He's pitching much better than Castillo right now, but he arguably pitched even worse in 2020 -- and wasn't as good in 2019, either. How could I possibly rank Ray ahead of Castillo? History didn't start six starts ago, and we can't just throw out the previous years because of their recent outlier performances.

So, that's where I draw the line. Ray is SP47, and that's where he'll remain, with Castillo slotting in one spot ahead of him. I don't feel terribly comfortable ranking Castillo even that high, but I also don't feel comfortable finally pulling the trigger on lowering him like that. 

Maybe I should have been lower on Castillo before this; maybe I should still be lower on him. But I'm not comfortable saying you should drop him yet, and I'm not comfortable writing him off as a potential ace. That is still there, he just has to fix what's wrong. He could do that in his next bullpen session and go on a roll, but after this week, you can't expect it.