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Jack Leiter: MLB Prospects Dynasty Pitcher Analysis for Fantasy Baseball

fantasy baseball prospects MLB prospects rookies call-ups

Welcome back RotoBallers to my deep dive on Jack Leiter. In this Dynasty Pitcher Fantasy Baseball Prospects series, I will focus on key pitching fundamentals as quantified by my FaBIO (Fielding and Ballpark Independent Outcomes) evaluation system (my RotoBaller debut article more fully explains the FaBIO methodology).

Every plate appearance is sorted into one of 12 event type bins (BB+HBP, K, IFFB, Pull OFFB, Center OFFB, Oppo OFFB, Pull LD, Center LD, Oppo LD, Pull GB, Center GB, Oppo GB) and the pitcher is charged with league's average runs value for that event type. Eventually, we wind up with a slew of fundamentals-rooted percentile ratings expressed on a 100 to 0 scale where 97 is plus plus, 84 is plus, 50 is average, and 16 is minus.

An all-in-one Overall Rating quantifies the pitcher's expected run avoidance per batter faced., but given our relative prioritization of fundamentals over run and hit outcomes before MLB we will commit more attention to its three core sub-Ratings of Control (or CTL, based on BB+HBP per PA), Strikeout (or K, based on K per PA), and Batted Ball Profile (or BBP, based on expected run avoidance per batted ball). Sub-Ratings of Batted Ball Profile like GB Rating (groundballs per batted ball), IFFB Rating (infielder flyballs per batted ball), and others yield insight into both approach and key characteristics of the fastball arsenal.

Editor's Note: Our incredible team of writers received five total writing awards and 13 award nominations by the Fantasy Sports Writers Association, tops in the industry! Congrats to all the award winners and nominees including Best MLB Series, NFL Series, NBA Writer, PGA Writer and Player Notes writer of the year. Be sure to follow their analysis, rankings and advice all year long, and win big with RotoBaller! Read More!


Jack Leiter, the Collegian

Jack Leiter rated just above plus overall (88th percentile Overall Rating) in the COVID-shortened 2020 D1 season over 4 appearances as a Vanderbilt true freshman against 60 non-SEC batters. Stronger areas included strikeouts, line drive avoidance, and opposite-handed batters' overall outcomes (all rated in 91st to 96th percentile). Weaker areas included outfield flyball avoidance (11th percentile) & control (41st percentile).

Leiter would assume a 2021 full-time weekend starter role alongside third-year sophomore Kumar Rocker and this Tweet summarizes how I evaluated Leiter upon a first look at the 2021 D1 FaBIO Ratings in early May.

And this analysis tweeted near the draft better summarized the complete pitching profile for the full 2021 D1 campaign.

Obviously, the many strikeouts were good. Also desirable was that he could get bonus infielder flyballs (IFFB have the same value as a K in run expectancy) atop the whiffs via the flatter approach-angled fastballs up. Additionally, he had two seasons of avoiding line drives rather well under his belt and had consistently rated well against opposite-handed batters, reducing future vulnerability to an opposing manager stacking a lineup in the direction of lefthanders.

Beyond leeriness of how relatively more walks and many outfield flyballs could coexist, I also knew that the only extreme flyball starting pitchers to consistently rank among MLB's top starting pitchers over the past decade were Max Scherzer and Justin Verlander, each of whom has a lot more control (less traffic on bases ahead of outfield flyballs) and a deeper and more functional offspeed arsenal than Leiter did then.

Cognizant of all of this, I had Leiter, who posted the 10th-highest FaBIO Overall Rating of 2021 NCAA D1 starting pitcher qualifiers, ranked as my #3 to #5 NCAA D1 pitcher in various incarnations of my 2021 Draftboard circa then with only Sam Bachman, Gavin Williams, Kumar Rocker (no knowledge of any medical flag then), and Gunnar Hoglund ahead of him.


Jack Leiter, the Draftee

With the first overall pick, the Pirates deployed a spread the bonus pool philosophy led off by moderately underslotting Louisville catcher Henry Davis at $6.5 million. The Rangers then stepped right into the trap of putting too many of their draft bonus eggs in the Leiter basket. That $7.9 million bonus turned out to be $1 million higher than the next highest of any draftee (high school righthanded pitcher Jackson Jobe) and a whopping twice what went to the next highest bonused D1 pitcher (Sam Bachman).

We would assume that the Rangers were not alone in their willingness to bonus Leiter at that level. As a second-year draft-eligible Division 1 pitcher, Leiter had both some unfinished product cache and extra signability leverage to wield, though he was totally going pro all along.


Jack Leiter, the Pro

Leiter wouldn't pitch in any official minor league games after the draft in the wake of Vanderbilt's deep postseason run to the championship series of the College World Series, but he would surface in a Rangers uniform come March 2022 and posted a not-so-unexpected mix of BB, LD, K, IFFB, and OFFB in one MLB spring training game appearance before going to backfield minor league games for the rest of March and April.

There were a few red flags from those tilts as some frames featured the awkward mix of louder aerial contact and walks while at least one was rolled due to the inability to complete it in a reasonable volume of pitches. Leiter would ultimately be assigned directly to Double-A when camp broke, almost as if the script had been penned months earlier.

Leiter did not overly impress upon the first look at 2022 MiLB FaBIO Ratings in earlier May, though he rated decently enough then over five starts per a 69 Overall Rating earned via 46 Control/85 K/37 Batted Ball Profile (5 GB, 40 IFFB, 62 LD Avoid, 2 OFFB Avoid, 34 PullOFFB Avoid). Much has gone downhill since, inclusive of the four-seam ride/carry properties that past D1 success so largely hinged on.

To date, pro Leiter has not done much to any of what a pitcher with his four-seamers up approach must do to succeed.

Half plus K might be sufficient in MiLB but falls short of the standard for a future MLB SP of this approach variety working in Double-A. A 23 IFFB Rating is far too low for so many outfield flyballs being struck. Combined that duo of ratings instructs that the 4-seam fastball's ride/carry traits are not nearly what they once were in NCAA. With control (CTL) and line drive avoidance (LD Avoid) each right around minus there is far too much traffic on the bases when the many outfield flyballs are hit.

Leiter is very fortunate to rate average at avoiding hits on batted balls (52 AVG) with a 23 IFFB and 15 LD Avoid. He is even more fortunate to rate half plus at avoiding extra bases (72 ISO) on batted balls with a 17 OFFB Avoid and 32 Pull OFFB Avoid (that his OFFB contact is actually biased in the late direction may be one redeeming quality). Leiter could easily look a lot worse on traditional hits and runs-referencing statistics than he does now. MLB batters will not be nearly so forgiving to a starter who sports the fundamentals he has flashed to this point of his pro career.

Carson Fulmer is a name that I have often considered invoking during my analyses of Jack Leiter but have yet to until now. The 8th overall pick of the 2015 MLB Draft was a very K-heavy yet wilder flyballer who also happened to be a shorter righthanded starting pitcher from Vanderbilt. What we saw then was Fulmer forced up the minor league ladder and into MLB by the White Sox when the underlying pitching fundamentals spoke against any of that.

Like Fulmer before, Leiter's D1 four-seams-up approach doesn't project so smoothly into a longer-term steadier-performing MLB starting pitcher future. The margin of error on collecting K+IFFB while avoiding BB+LD gets very thin around the pending threat of so many outfield flyballs producing extra base events, even so in this season of reduced flyball carry.

Beyond simply learning to locate his four-seam to other areas of the strike zone with effect, Leiter also seems in need of at least lightly diversifying the fastball arsenal via a two-seamer else cutter (a former specialty of his MLB father, Al). That probably makes him less of an impact K standout ahead. Rehabilitating the fastball arsenal should take priority now over what to do next with one or more offspeed offerings. Barely 12 months removed from being drafted this would-be 2022 third-year collegian now resembles a more involved renovation project than one would ideally invest $7.9 million in.

Maybe if things broke better for him ahead, a flyball-leaning MLB starter similar to Tyler Mahle could result. Or perhaps even if the K+IFFB versus BB+OFFB bias mostly held a more volatile back-of-rotation Lucas Giolito/Freddy Peralta/Cristian Javier/Taylor Widener style of starter could be in play. Of course, a Carson Fulmer journeyman outcome could just as easily come to pass if Leiter's professional development tracks too similarly to how Fulmer's did and attempts to improve the fastball arsenal fail to bear fruit a la Fulmer. Unless Leiter recaptures the ability to get whiffs and popups via the four-seamer that propelled his name toward the top of many 2021 MLB draft boards, he would not even be in play as an impact relief candidate.


Relevance to Fantasy Baseball Leagues

Dynasty league owners should seek to trade Leiter soon before too many competitors recognize that the underlying pitching fundamentals are presently much worse than the traditional stats may lead one to believe. The cleverest among current Leiter owners will disguise this as a pursuit of a fantasy pennant over the season's final two months.

As in real life, it is tougher to trade last year's second overall pick for full value while rebuilding a franchise, though perhaps the serial trader of the circuit would take the bait. Dynasty non-owners should simply let the stock fall until some threshold is crossed for which buying low as a rebound candidate makes sense per the composition of the franchise's organizational roster.

Nor should Leiter be prioritized on draft or auction lists for 2023 fantasy leagues of other formats as the volume of pitcher development work to be completed between now and the end of that season skews too large.

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