Reviewing the Rookie Pitchers — Through June 12, 2023

Let’s review some of the rookie pitchers, all of whom were top prospects heading into the season.

Eury Pérez is a large man. Standing 6’8″ and possessing a high 90s fastball, to go along with a slider as his primary secondary pitch, comparisons to Randy Johnson, but right-handed, would seam apt. He’s just 20 years old and completely skipped Triple-A when he debuted with the Marlins. In the minors, he never posted a strikeout rate below 31.3% and his SwStk% sat in the mid-teens or higher. Of course, the sample sizes in his professional career have all been small, but he’s absolutely dominated over his short career so far.

He’s made six starts in the Majors so far, accumulating 29 innings, and has posted some interesting metrics. First off, don’t be blinded by the 2.17 ERA, as he has benefited from some great batted ball luck. Both his SIERA (4.54) and xERA (3.66) are significantly above his 2.17 ERA, thanks to a .243 BABIP and inflated 91.8% LOB%. His strikeout rate has also been kind of meh at 24.8%, while his walk rate has jumped into double digits. Finally, he has been an extreme fly ball pitcher, would could result in gopheritis, and multi-run home runs given the high walk rate.

So that’s the bad news, as his debut so far has been more “fine” than “impressive”. However, he has generated a 13.1% SwStk%, which is excellent, and that has been driven by three secondary pitches that have recorded double digit SwStk% marks. That’s really exciting. His slider has been very good, albeit not elite, with a 17.5% SwStk%, while his curveball has been incredible, with a 27.5% SwStk%. With that kind of pitch mix, and a high 90s fastball that peaked at 100 MPH, the future seems amazingly bright.

Bobby Miller was the Dodgers’ second ranked prospect and 31st overall, but somehow managed to convince the team to call him up for his MLB debut despite a bloated 5.65 ERA in 14.1 innings this season. So much for earning a promotion! Miller’s historical record has been interesting and makes it tough for me to gauge his potential. His Triple-A SwStk% marks have been unimpressive, but he did still posted a strikeout rate over 30% at the level last year, which means he was either super lucky, or induced a ton of called and/or foul strikes. It doesn’t make me very confident he could maintain a high strikeout rate if he’s not inducing swings and misses.

So his strikeout potential is a bit sketchy at the moment, and that will go a long way into determining how good a prospect he actually is. The projections right now share my concerns as the most optimistic is forecasting just a 23.1% mark. That’s fine and dandy, but nothing to get too excited about. I’m guessing a lot of the hype comes from the fact he is averaging 98.8 MPH with his fastball. So regardless of his history, the hope is that he could convert that elite velocity into whiffs. It hasn’t happened yet in the Majors, as his four-seamer’s SwStk% stands at just 5.9%, which is below average. However, his slider has been fantastic with a 21.3% SwStk%, while his least used curveball is up there at 18.9%.

I love his high ground ball rate, as that could erase some extra baserunners with double plays and offset some strikeout rate downside while he learns how to use the fastball to generate more swings and misses. I do like the potential here, but I think it’s more future upside we’re hoping to see than a valuable fantasy starter right now. Also, don’t forget that his seemingly amazing MLB start with a 0.78 ERA is entirely driven by the trio of a .211 BABIP, 0 home runs, and a sky-high 89.5% LOB%, none of which will last.

The Astros’ top prospect, Hunter Brown debuted last year, making two starts and spending the rest of his time in the bullpen. He showed exciting potential with strikeout ability and an elite ground ball rate. This year, it has been more of the same, even as he has spent the entire season in the starting rotation. Though he still hasn’t impressed with his SwStk%, he has generated a high enough rate of called strikes to still post a strong strikeout rate. How long that will last is anyone’s question, as called strike rate is a bit less sticky from season to season than swinging strike rate is.

He’s another hard thrower, averaging 96.1 MPH with his four-seamer, and then mixing in a slider and curveball. The slider just hasn’t generated the whiffs you might expect, especially one that graded out as 60/60. The curveball has been good, but again, I would expect a bit better than a 16% SwStk% from a pitch rated 70/70. Both pitches have generated a ton of grounders though, so that’s a plus.

Brown seemingly has the type of skill set I love to see, combining strikeouts and ground balls, while his walk rate hasn’t been an issue, with room for improvement. While I’m skeptical he can maintain this high a strikeout rate unless he starts inducing more swings and misses, it should remain good enough to ensure he delivers solid fantasy value.

By SIERA, Taj Bradley has the best skill set of the group, but the highest ERA…go figure. That’s what happens over small sample sizes! Though Bradley’s Triple-A strikeout rates have been quite unimpressive and nowhere close to what you want to see from a top prospect (21.5% in 2022, 16.7% in 2023), his SwStk% have been a bit better around 12.5%. Still no great shakes, but they suggest better strikeout rates than what he posted at the level.

At the risk of sounding like a broken record, Bradley also throws hard, averaging 96.2 MPH with his four-seamer, while also mixing in a bunch of other fastballs, such as a cutter and splitter, plus a curveball. All of his pitches have generated a double digit SwStk%, though none have stood out yet for being elite for the pitch type. Surprisingly, his best whiff pitch has been his splitter, which he has thrown least of all. I think I might be least excited about his future of the four in this group, as he doesn’t have the high ground ball rate and his repertoire doesn’t appear as exciting as some of the others.