Getting to Know: Concerns Regarding The Cardinals’ Jack Flaherty Ahead Of His MLB Debut

by Eric Stashin (aka The Rotoprofessor)

It was a bit of a surprise when the Cardinals traded Mike Leake earlier this week, though they do have depth in the rotation and the move frees up money for the next few seasons.  One of the benefactors of the move will be one of the team’s top prospects Jack Flaherty, who will be recalled tomorrow to start against the San Francisco Giants.  Could he hit the ground running and make a September impact?  Let’s take a look and try to determine exactly what his upside may be:

Rotoprofessor Rankings:
Cardinals’ #6 Prospect

Throws – Right-Handed

Age – 21

2017 Statistics:
Double-A – 63.1 IP, 1.42 ERA, 0.92 WHIP, 8.81 K/9, 1.56 BB/9
Triple-A – 85.1 IP, 2.74 ERA, 1.14 WHIP, 8.96 K/9, 2.53 BB/9

What Others Have Said:
There are certain expectations with young projectable-looking high school pitchers, that they’re going to add a ton of velocity as they mature. That was slow in coming with Flaherty, who had been more steady and consistent than exciting as a prospect, though he did start throwing harder in 2017, touching the mid-90s more consistently. He has three usable secondary offerings as well. His changeup could eventually be a plus pitch as his best option and he’ll throw both a solid slider and a slow curve to keep hitters off-balance. –

The news that Flaherty’s stuff has taken a step up this season is a promising one, as it has clearly translated to the field.  That said he’s shown strikeouts (career 8.9 K/9) and control (career 2.6 BB/9) since being drafted in the first round of the 2014 draft.  It doesn’t mean that they are guaranteed to continue at the highest level, as there are multiple questions he faces ahead of his first taste of the Majors:

Can he maintain the strikeouts?
It’s not a given, considering his rather pedestrian 9.4% SwStr% at Triple-A.  That’s not to say that he doesn’t have the upside of maintaining nearly a strikeout per inning, but it also wouldn’t be surprising if he’s closer to the 7.5 range this season.

Can he maintain the control?
Obviously he was elite at Double-A this season, but the walks have jumped since his promotion.  Facing even more developed hitters, could they lay off his pitches a bit more?  While it wouldn’t be a bad number, would a walk rate of around 3.0 (or maybe a little bit more) be shocking?

Can he keep the ball in the ballpark?
His groundball rate at both levels he’s played this season is average at best:

  • Double-A – 40.0%
  • Triple-A – 41.0%

It hasn’t been a significant issue to date, but he could struggle with home runs in the Majors.

It all comes together for a decent starting pitcher, but one that wouldn’t likely be a difference maker.  Any young pitcher has the potential to be inconsistent, and considering the concerns it’s going to be hard to expect an overall stellar line from Flaherty.  Could he be lights out?  Absolutely, thanks to unfamiliarity, but don’t expect it.

Preseason Grade – B
Current Grade – B

Sources –,, Fangraphs, Baseball Reference

Make sure to check out our Mid-Season Top 50 Prospects by clicking here!

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