Spotlight on MLB Spring Training Pitcher Fundamentals

If ever there was a time to ignore runs and hits and shift attention more directly onto pitching fundamentals at the core level, MLB spring training just might be it.

Blinding sun and skies and stadium-unobstructed winds can turn sure outs into hits. Arizona infield surfaces tend to play rock-hard relative to Florida ones. Minor leaguers are shifted all around the field to play positions not so familiar to them. Smaller sample sizes of batters faced (plate appearances) also cause hits and runs outcomes to vary widely.

In this article, I highlight who stood out this spring at fundamentals-rooted pitching outcomes as quantified by the FaBIO model.

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Brief Explanation of the FaBIO Model

My Fielding- and Ballpark-Independent Outcomes (FaBIO) pitcher evaluation model sorts every plate appearance into one of 12 outcome bins (BB+HBP, K, IFFB, Pull-Third OFFB, Center-Third OFFB, Oppo-Third OFFB, Pull-Third LD, Center-Third LD, Oppo-Third LD, Pull-Third GB, Center-Third GB, Oppo-Third GB) and credits the pitcher with their league's mean runs value for said particular event that season. The most runs-punitive events for pitchers are Pull-Third OFFB, the three line-drive types, and BB+HBP. The most runs-preventing events for pitchers are K, IFFB, and Pull-Third GB.

Dividing their total number of expected runs by batters faced (BF) yields expected runs per batter that can be percentile ranked relative to the league mean and standard deviation for that parameter amongst league qualifier starters (else relievers) to arrive at their Overall Rating.

Its three subcomponents of Control Rating (CTL, based on BB+HBP per BF), Strikeout Rating (K, based on K per BF), and Batted Ball Profile Rating (expected runs per batted ball) are also reported to understand better the path the pitcher traveled to reach their Overall (reverse engineering Overall reveals that expected run avoidance is generally 44% Strikeouts, 34% Batted Ball Profile, and 22% Control).

To better understand the path to Batted Ball Profile, we will also examine percentile ratings for select batted ball event types (on a per batted ball basis). Lastly, to check how well expected batted ball outcomes matched real-world ones, we will compute percentile ratings for the avoidance of hits (AVG) and isolated power (ISO, or simply extra bases) on batted balls (recognizing full well that these two parameters are neither fielding- nor ballpark-independent outcomes).

A percentile rating of 97 amounts to plus-plus (two standard deviations above the mean), 84 is plus (one standard deviation above the mean), 69 is half plus, 50 is average, 31 is half minus, 16 is minus, and three is minus-minus.

Starting Pitcher Qualifiers who Posted Plus Overall Fundamentals

The 33 pitchers who appear in the next table met my SP qualifiers criteria (36+ BF, 9+ BF/G) and rated plus in Overall Rating (expected run avoidance).

History instills that much more trust in those who land here and were already considered on this level prior to the spring. For the relative surprises, bet the over versus preseason expectations but do not expect them to suddenly be great until regular season data supports such a stance. And every so often the relative spring surprise turns out to be a regular-season breakout star (Robbie Ray and Carlos Rodon come to mind from past springs).

What if, just maybe, Gavin Stone, who I described as similar in design to Yoshinobu Yamamoto in my recent NPB-focused article, wound up a better all-around fundamentals '24 MLB SP than the Dodgers' offseason NPB transfer portal signee? Imagine how tough it would be to defeat the Dodgers in '25 when they could trot out Tyler Glasnow, Yamamoto, Shohei Ohtani, and (also in this table) Bobby Miller behind new staff ace Stone. With Stone also finishing #5 at FaBIO Overall among '23 MiLB SP qualifiers, these sterling spring fundamentals make it all the easier to attribute his ugly '24 MLB mini-debut (152 BF at 19 BF/G: 4 Overall, 32 CTL/8 K/14 Batted Ball Profile) to other factors (stagefright, pitch tipping, etc.).

It is quite something for A.J. Puk to land here after never starting a single game in his MLB career. After logging 257 BF at 4 BF/G in 2023 MLB+MiLB action, what sort of increased '24 workload could he endure more healthily? Starter or not, Puk was indeed already a more fundamentally well-rounded pitcher as evidenced by 2023 MLB 4 BF/G 98 Overall (93 CTL/91 K/77 Batted Ball Profile).

Mitch Spence lands here with Rule 5 Draft restrictions in place. If he can survive the teeth-cutting phase of his Oakland debut (not be returned to Yankees), he could emerge as a viable "some K, loads of GB" mid-rotation SP whose fringier CTL isn't so runs-punitive owing to the K else GB bias among his non-BB+HBP outcomes (2023 AAA 703 BF at 24 BF/G: 88 Overall, 83 CTL/58 K/83 Batted Ball Profile; 91 GB, 15 IFFB, 88 LD Avoid, 69 OFFB Avoid, 74 Pull OFFB Avoid). Like any other Athletics SP, lots of wins would not be in the '24 forecast even in the presence of above-average pitching fundamentals put up over thirty starts.

Cardinals rooters are already frustrated over the springs of Jack Flaherty (2023 MLB: 18 Overall, 8 CTL/58 K/7 Batted Ball Profile) and Jordan Hicks (2023 MLB at 4 BF/G: 71 Overall, 23 CTL/72 K/77 Batted Ball Profile; 95 GB, 14 IFFB, 72 LD Avoid, 94 OFFB Avoid, 93 PullOFFB Avoid). But let's see this historically shakier-at-fundamentals duo replicate their spring resurrections in the regular season before fully buying them as this caliber of MLB SP.

At the opposite end of the spectrum, it would seldom be advisable to release an established veteran SP from a fantasy squad on the grounds of a fundamentally bad spring. But such a poorer showing ought to at least plant seeds of doubt and more so if their '23 ended on bad fundamentals terms and/or their '24 regular season gets off to a bumpier start in that realm.

Relief Pitcher Qualifiers who Posted Plus Overall Fundamentals

Relievers, by nature, run hot and cold. Most of them would still be starters otherwise.

Applying a qualifier criteria of 27+ BF and under 9 BF/G, these MLB spring RP qualifiers rated plus at Overall Rating.

Is Ian Hamilton already the 2024 Yankees' most impactful high-leverage RP (2023 MLB: 80 Overall, 32 CTL/73 K/88 Batted Ball Profile)? Being outrighted off the MLB roster in September and re-signed on a MiLB deal seems to have awakened the sleeping giant in not yet re-rostered former top SP prospect Tony Santillan.

How productive of a 2024 fantasy RP does Griffin Jax (2023 MLB: 85 Overall, 77 CTL/52 K/90 Batted Ball Profile) prove to be during and after the injury-related absence of Jhoan Duran? Are Athletics comfortable with Mason Miller (2023 MLB 139 BF at 14 BF/G: 68 Overall, 3 CTL/87 K/83 Batted Ball Profile; 2023 AAA & AA & A 70 BF at 10 BF/G: 100 Overall, 95 CTL/100 K/15 Batted Ball Profile) staying a reliever or will standout fundamentals like these tempt higher BF/G stints? Hunter Harvey (2023 MLB: 86 Overall, 92 CTL/73 K/50 Batted Ball Profile) seems a potential breakout fantasy star between the K and Path to Batted Ball Profile fundamentals seen here.

Walter Pennington (whose Batted Ball Profile would better match GB if LD Avoid was more typical of what that level of GBer posts) is not yet rostered but should be fairly soon, at which time he and James McArthur (2023 MLB 90 BF: 99 Overall, 99 CTL/53 K/100 Batted Ball Profile) will form one of the more formidable MLB RP duos whose names also sound like those of Civil War era generals. 2022 MiLB FaBIO SP superstar (#1 among MiLB SP Qualifiers via a 100 Overall) Landen Roupp rated well enough around batted ball profile problems in an injury-shrunk 2023 AA campaign (120 BF, 12 BF/G: 82 Overall, 63 CTL, 99 K, 0 Batted Ball Profile) before earning his way onto the 2024 MLB Opening Day roster via these fundamentals.

The plus or better Overall RP below represents the #25 through #48 RP qualifiers by Overall Rating. The challenge with this crowd is to first distinguish potential future fantasy league valuables from fringy MLB+MiLB journeymen, then identify who could more realistically replicate these levels of fundamentals in a regular season over multiple months.

Yes, Eury Perez and (likely) Luke Weaver are 2024 SP rather than RP. As was true in the 2023 MLB debut, Perez continues to expose himself to rather extreme Pull OFFB (and thus ISO) risk around strong K+CTL outcomes.

Individual Pitcher Analysis: Alec Marsh, RHSP, Kansas City Royals

Over four MiLB seasons and a short Arizona Fall League stint, strikeout specialist Marsh posted five K Ratings in the range of 77 to 100. That his 2023 83 AAA & AA K Rating dropped only to 71 in MLB affirmed that his K weaponry was indeed MLB-caliber. But half minus (32) CTL and a minus (15) Batted Ball Profile in 2023 MiLB predisposed him to worse than minus-minus (2) CTL and (1) Batted Ball Profile Ratings that ultimately sank his MLB debut Overall to a measly 9 mark.

But the 2024 MLB spring training version of Marsh flashed a more complete FaBIO profile featuring a plus (85) Batted Ball Profile anchored by a plus-plus (98) GB Rating, fringe-average (44) CTL, and still half plus K (69). Royals ultimately rewarded this far more dimensional out-generator with a rotation spot to open the year. Given these new developments, we ought not to be surprised if Marsh were able to post an Overall Rating in the range of average (50) to half plus (69) on the strength of a mix of K and GB. Marsh has two option years remaining to begin in 2024, so the opportunity exists to pursue further development at the AAA level should that be needed ahead.

Individual Pitcher Analysis: Matt Manning, RHSP, Detroit Tigers

Manning spent some time in both AAA and MLB in each of the last three seasons and seems surer to do it again in 2024 after being optioned at the end of spring camp. While in MLB Spring Training, Manning posted a much improved 81 K Rating that is higher than any he had put up in post-pandemic MLB or MiLB seasons and especially higher relative to the paltry 2023 MLB 5 mark.

Upon return to MLB, Manning could perhaps post a K Rating in the neighborhood of half plus (69) with plus or better hit (AVG) avoidance thanks to a stouter mix of LD Avoid + IFFB fundamentals. CTL may indeed flip to under 50 to enable those extra K (via more chases), while ISO (extra bases) avoidance on batted balls would also logically rate in the range of half minus to average based on the '23 MLB and '24 MLB ST OFFB Avoid and Pull OFFB Avoid duos.

A 2024 MLB Overall that rates closer to half plus (69) than average (50) would not be too unreasonable. Manning would still have an option year in the tank if he lost the second one after hitting 20 days in MiLB on option assignment during 2024, so there is MLB+MiLB development time that can be used to round him into a better all-around starter than we have seen to this point of his MLB career.

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