By : Dave Andersen

Some pros: 

First things first: I love Jack Flaherty. More precisely, I love his ability to strike out batters with his filthy slider. I don’t think, however, that he’s a great—or even good—source of quality starts this year. The 23-year-old strikeout artist owns one of the nastiest sliders in the game and proved it in his age-22 campaign in 2018. The kid has the stuff of an ace: a solid three- or four-pitch arsenal (if you count his changeup, which I’m reluctant to), veteran-like intensity and composure on the mound, increased velo on his fastball (according to reports from Spring Training), and—thanks in large part to his nasty slider—the ability to rack up K’s by the truckload. In 2018, Flaherty’s slider generated an elite 23% swinging strike rate with a pVal of 8.4, which would’ve ranked 14th behind that of Cookie Carrasco had he thrown enough innings to qualify. 

More pros: 

With a SwStrk rate of 13.4% in 2018, the aforementioned slider, and a solid curveball that I expect him to throw more often, 2019 could be a year in which Flaherty punches out 200+ batters and finishes as a top-15 SP in roto and/or categories- or points-based formats. Flaherty did, after all, record 181 K’s in 151.0 innings at the MLB level in 2018, and his xFIP of 3.58 supports his sub-3.5 ERA. And with a 10.85 K/9 and K rate of 29.6%, there’s no question he has the stuff to join the elite strikeout pitchers of MLB. 

While there’s no doubting his brilliant 2018 or his upside moving forward, there are some holes in his game—holes that should give those of us searching for quality starts pause. What holes do I speak of? In short: command, command, command.  

The con(s): 

Flaherty can be woefully inefficient: he averaged a dreadful 4.21 P/PA last year, and his first pitch strike rate (FPK) of 57.2% was almost embarrassing. At 17.1 pitches per inning along with a 10% walk rate and BB/9 of 3.52 (which would’ve tied for ninth-worst in MLB had he qualified), Flaherty’s ability to go deep into games appears questionable at best. Further, the Cardinals are sure to keep an eye on his innings this season as Flaherty exhibited major signs of fatigue in his last three starts of 2018, over which he surrendered 12 earned runs and seven walks across 12.2 innings. 

Across Flaherty’s 28 starts in 2018, only 10 were of the “quality” variety. While some of his poor start-to-QS ratio was likely due to Cardinals’ management treating Flaherty’s innings—and especially high-stress innings—with caution, his command must improve if he’s going to join the likes of elite innings-eating pitchers who routinely post 18-20+ quality starts per season. In 2018, for instance, 11 pitchers earned 20+ quality starts and 19 earned at least 18. Note, however, that not all 19 of these QS-machines were elite pitchers; what they were was something that Flaherty is most certainly not: efficient. 

Flaherty’s ability to miss bats is unquestioned, but can he become an efficient, 180+ inning pitcher with 15-20 QS in 2019? His command metrics suggest not—not yet, at any rate. To join the increasingly small number of pitchers who go deep into games, Flaherty must dramatically improve his FPK rate to consistently get ahead in counts, record quick outs, and walk fewer batters. In other words, if his inextricable metrics of FPK, BB/9, and P/PA don’t improve—and I’m bullish that they will, to an extent—then we could be looking at another subpar quality start season from Flaherty, which isn’t going to move the needle in leagues that count QS. 

While ESPN projects 21 QS from Flaherty this year, ESPN is notorious for projecting plentiful quality start totals from any decent starter. For a more realistic outlook, Baseball HQ projects 13 QS while Rotowire projects a lowly total of nine. These projections do, however, come with similar ratios to those in 2018, a small bump in IP, and a brilliant K % and K/9. Make no mistake: Flaherty won’t hurt you in any format this season, but if you’re looking to build a staff that delivers lofty QS totals, Flaherty likely isn’t the answer—not this year, anyway. 

*Stats courtesy of Fangraphs,,, and