I’m not that worried about Mitch Keller’s recent struggles. At least not in the sense of his long-term upside.

Keller gave up three runs and walked five batters in four innings on April 28th. He rebounded in his next start with a good outing, but struggled again in his last start, leaving after 4.1 innings with four earned runs, three walks, and one strikeout. He’s had some control issues this year, leading to 17 walks in 34 innings, which were amplified by those two starts. Control typically isn’t his problem, and wasn’t an issue for him last year in Altoona.

Typically with prospects, I try to ignore the short-term bumps in the road. They happened with guys like Gerrit Cole, Jameson Taillon, and every other pitching prospect. If a problem goes on for an extended period of time, we start to focus in on the possible cause. But it’s important to step back and have perspective here. Keller’s bad starts recently seem worse because we’re in the moment. No one remembers similar bad stretches from Cole or Taillon during their development, because once you’re out of the moment, they didn’t turn out as bad as expected.

I’ve seen enough of Keller, both this year and in previous years, to believe he’s got the stuff to be an impact starter in the majors, and a top of the rotation guy. But there’s one thing that does concern me, and that’s whether he can be a top of the rotation guy with the Pirates.

Gerrit Cole was traded to the Astros this year, and in that process, it revealed a flaw in the Pirates’ way of pitching. Cole is now throwing his curveball and slider almost 40% of the time, and reducing the usage of his fastball to below 60%. Most Pirates pitchers, including Cole while he was here, throw their breaking stuff less than 30% of the time, and throw their fastball over 60% of the time.

The Astros, on the other hand, have seen a trend where almost all of their pitchers are throwing their fastballs closer to 50% of the time, and using the breaking stuff about 40% of the time. It’s hard to argue with the results, especially when Cole has turned into the Cy Young candidate everyone expected him to become, and Charlie Morton is putting up some of the best numbers of his career with that approach.

The approach makes sense. Hitters today are focused on lift and launch angle, and hunting fastballs to hit for power. Throwing more breaking stuff can counter this trend, and when you have really good breaking stuff like Cole, you’re doing yourself a favor by throwing the slider and curveball more often. It’s a simple concept: Throw your best pitches more often, and you’re more likely to see success.

The Pirates used to follow this approach. They had reclamation projects like A.J. Burnett, Francisco Liriano, and Edinson Volquez switching to a two-seam fastball, and that worked for those guys because their two-seamer was better than the four-seamer. It wasn’t a two-seamer approach that worked. They had J.A. Happ drop his two-seamer and focus primarily on the four-seamer when he arrived, which again, was his better fastball.

Throwing your best pitches is one thing, but the extreme fastball usage is looking like an out-dated concept, and Cole might be the poster boy for this.

Unfortunately, I could see a scenario where Jameson Taillon eventually becomes the next Cole.

Taillon’s best pitch is his curveball, but he’s throwing that 21% of the time this year, while throwing his fastballs around 70% of the time. His career so far has looked similar to Cole’s career with the Pirates. He shows flashes of being a top of the rotation guy, but hasn’t consistently been a dominating pitcher, and hasn’t been a guy you could consider one of the absolute best in the game.

I think Taillon can get there, and my fear is that he will eventually follow the same path as Cole, go somewhere else, and unlock his full potential.

Likewise, I can’t think about Mitch Keller’s development without thinking that he would be the next in line. A guy with top of the rotation stuff who the Pirates are hoping to lean on to lead their future rotation, but who might not unlock his full potential with the team.

If you thought the heavy fastball usage was just a Ray Searage thing, you’re wrong. It’s a system-wide strategy. Keller uses the extreme fastball approach more than most, despite having a plus curveball and an improved changeup. If that continues to the majors, I could see this whole situation playing out again.

Fortunately, the Pirates have plenty of time with each guy. They have Taillon under control through the 2022 season. If Keller made it up this year, he would be under control through the 2024 season. So there’s plenty of time to adapt to the new and more successful trend with each pitcher.

The question is whether the Pirates will make that adjustment. Most of their comments about Cole so far have been dismissive that the increased breaking stuff is the cause of his success. Clint Hurdle avoided the topic earlier in the year, saying he hasn’t seen what Cole was working on and can’t comment. Ray Searage chalked it up to Cole not being relied on to be the leader of the staff. But it’s hard to ignore the massive switch in the approach with Cole, just like it’s hard to ignore the same thing from Morton, who was never asked to be the leader of the Pirates’ staff, and is now putting up great results with the Astros.

Hopefully the Pirates make the switch with Taillon and Keller. You could argue that they already wasted one top of the rotation guy by not getting the best out of Cole. I like the return they got for Cole, but the best thing that could come from that trade is the realization that their approach to pitching is flawed after seeing Cole’s success with a new approach. It would be a major disappointment if they don’t capitalize on that and make a change in their ways.