Reviewing the Rookie Pitchers — Through Jul 22, 2023

Let’s finish reviewing the rookie starting pitchers with a trio that have posted underwhelming results so far. Two of these three names were former top prospects. Let’s find out whether it’s worth sticking with them.

Brandon Pfaadt | ARI

The 4th ranked Diamondbacks prospect and 23rd overall, Pfaadt was first recalled in early May and made five starts during the month. After weak results, he was returned to the minors and then came back for a spot start at the end of June, which went poorly as well. Alas, he’s now up for a third time and his last start was at least strong enough not to immediately get demoted again.

It hasn’t been easy for the top prospect, as he’s finding that striking out MLB hitters is far harder than punching out minor leaguers. His strikeout rate, typically in the high 20% or low 30% range in the minors, backed by mid-teen SwStk% marks, has slid to just 18.5% with the Diamondbacks. His 11% SwStk% is right around the league average, but we expected better.

With scouting grades suggesting two above average pitches and two around average, with the potential for more, he seemingly has the repertoire to miss bats. And heck, one look at his SwStk% pitch splits, and you wonder how he has only managed an 11% SwStk%! His slider, changeup, and curveball have all generated mid-to-high teen SwStk%. That’s fantastic! His four-seamer, though, is only at a 6.5% mark and he has thrown it just over half the time. Still, it seems like this mix should be resulting in a higher SwStk%. But it’s still good news as he clearly is getting swings and misses with three non-fastballs, which is a big deal.

Throughout his professional history, he has allowed a high rate of line drives. Unfortunately, that has continued at the MLB level, as he has posted a 26.2% LD%. That’s really high and increases the risk he posts a high BABIP. He has offset it somewhat with a high FB%, but oddly a low IFFB% means he’s not benefiting from those flies as much as you would expect. The control has been good, as suggested by his minor league record, so that’s a positive.

Overall, I’m intrigued by the three pitches generating mid-double digit SwStk%, combined with his good walk rate. The high FB% isn’t that big a deal as it should result in a lower BABIP, but the high LD% is a big deal and he’s never shown the ability to limit that rate. I have real mixed feelings here, as there are several positives, but also some major red flags.

Grayson Rodriguez | BAL

With a 70/70 grade changeup to go with a 60/60 fastball and two other pitches that figure to at least be average, Rodriguez was one of the most exciting pitching prospects in the minors. Unlike Pfaadt, the strikeouts have mostly been there for Rodriguez, though interestingly, his SwStk% is barely higher and his CSW is actually nearly identical. There definitely shouldn’t be this large a gap between the strikeout rates. Given the current swinging and called strike rates, it would seem Pfaadt has been unlucky, while Rodriguez has been lucky, to be posting the strikeout rates they have. Of course, I think we all expect the SwStk% marks to rise for both.

Similar to Pfaadt, Rodriguez was up earlier in the year (actually starting the season in the team’s rotation), but was ultimately demoted due to poor results in late May. He has since been recalled again and has made two starts.

Rodriguez has averaged 97 MPH with his fastball and has complemented it with his signature changeup, slider and cutter, with a lesser used curveball. All three of his most frequently used pitches have generated double digit SwStk% marks, which is good. However, perhaps we expected more from his 70 grade changeup than just a 14.2% SwStk%. In addition, his slider has generated a below average mark for the pitch. His cutter has been awful at inducing swinging strikes at just a 4.6% mark and has gotten absolutely demolished, allowing a .531 wOBA. He either needs to improve that pitch in a hurry, or just stop throwing it.

Since the strikeout rate sits in the mid-20% range, we have to go somewhere else to find out why he has posted an ugly 6.91 ERA so far. His 9.9% walk rate ain’t great, but certainly not a killer. Like Pfaadt, he has also allowed a high LD%, though not nearly as high, while generating a low rate of pop-ups. This time, the line drives and lack of pop-ups have really inflated his BABIP, which sits at .369. He also hasn’t been able to keep his fly balls in the park, allowing an absurd 24.5% HR/FB rate. But the 6.12 xERA kinda confirms that the contact quality he has allowed has been powerful enough that bad luck is hardly to blame.

It’s hard to ignore the high SwStk% marks he has posted throughout his minor league career ,along with the consistently high strikeout rates, which never fell below the 33.1% he posted at Triple-A this year, if you ignore his Rookie league debut in 2018 over just 19.1 innings. He clearly has the fastball going for him, so the optimistic view is he starts getting better whiff rates on his changeup and slider. The control hasn’t been great this year, but it’s been much better in the past. I think he’s a better and safer bet than Pfaadt, particularly because he’s not an extreme fly ball pitcher prone to multi-homer games.

Reese Olson | DET

Olson has the least prospect pedigree of this trio, ranking just 12th among Tiger prospects and failing to make the top 100. But he also came with a 70/70 graded changeup, along with averageish to above average grades on his three other pitches. Somehow, a 6.38 ERA at Triple, and ERA marks that were never better than 4.14 throughout his pro career, were enough for the Tigers to deem him ready for an opportunity at the MLB level. At least we know the front office looks deeper than ERA, but it’s still not something you see very often!

On the surface, it looks like Olson has enjoyed quite a nice debut with his 25.1% strikeout rate and 5.6% walk rate. That walk rate is quite surprising, actually, as he has posted double digit marks at four different stops, including a 12.6% mark at Triple-A this year. Did he just suddenly learn control after waking up one day? Seems so! A 12% SwStk% and 29.2% CSW% are super solid and supports his strikeout rate.

His slider has been elite, generating a 21% SwStk%, while his changeup has been excellent at a 17.2% SwStk%. However, his four-seamer and sinker, along with his little used curveball, have all generated below pitch average SwStk% marks in the low-mid-single digit range. It’s odd that his fastballs have generated such poor SwStk% marks considering he has averaged 95 MPH with them.

While he has oscillated between being a ground ball pitcher and posted a neutral, league average batted ball profile, he has suddenly become a fly ball pitcher. It has helped his BABIP, but isn’t so great when allowing a 13.2% HR/FB rate.

Above, I mentioned that on the surface it looked like he was enjoying a nice debut. Welp, the final of the luck metric trio, LOB%, is where we learn what has gone wrong. He has posted just a 62.8% LOB%, which means a significantly higher percentage of his baserunners has scored than the league average. Interestingly, he has struggled with LOB% throughout his entire career and has posted just a 70.3% mark at his best. I don’t know what might be causing it, but you would think it’s an issue the Tigers would be able to identify and address.

I don’t know if his control problems will return, but I’m pretty intrigued here given the whiffiness of his slider and changeup so far. I would be more nervous about his low fastball SwStk% marks if he wasn’t throwing 95 MPH.