The first two graphs and first three tables below detail how high school pitchers selected in and/or signed from the 2017 MLB First-Year Player Draft class stacked up against their MiLB league's starter or relief peers per my Fielding and Ballpark-Independent Outcomes (FaBIO) statistical evaluation system. The usual caveats apply, and in this particular case the batters faced samples skew very small given that these pitchers were pros for little more than 2 months and their workloads tend to be carefully monitored (kids being handled with kid gloves). For what remains of the FanPost, I will delve into how various prep pitching debutants have rated on the FaBIO scales dating all the way back to the 2013 minor league campaign.
.
Methods
Each nonbunt plate appearance is sorted into 1 of the following 12 categories, and the pitcher is charged with the league's typical 2017 runs value for said event.
1. BB or HBP, 2. K, 3. IFFB, 4. GB to pull-third, 5. GB to center-third, ..., 7. LD to pull-third, ..., 12. OFFB to oppo-third
Each pitcher's final runs per plate appearance value is compared to the league peer group's mean and standard deviation for that parameter to obtain their Overall Rating (which can be further split to examine how each pitcher performed against opposite-handed batters, OHB, and same-handed batters, SHB). A Batted Ball Rating is determined similarly after omitting all BB+HBP or K events (individual components of the Batted Ball Rating are also computed such as GB Rating, IFFB Rating, etc., using GB per batted ball, IFFB per batted ball, ...). A Control Rating (using BB+HBP per PA) and K Rating (using K per PA) are also determined. A Youth Rating is determined by comparing the pitcher's age relative to the mean and standard deviation for that role (SP or RP) in their league (the reliever sample in a league tends to be a year or two older, on average).
Each rating will be expressed on a 100 to 0 scale where the number indicates the expected percentage of league peers beaten on the stat. 50 denotes league-average, with 84 being one standard deviation above league-average ("plus", indicated by a green number in tables) and 16 being one standard deviation below league-average ("minus", red number in tables). Asterisks denote southpaws.
.
Results
Prep Pitchers Signed from Rounds 1 Through 10, Overall Ratings Plotted Chronologically by Draft Order
Performance in terms of Overall Rating within this group tended to skew toward the extremes, with far more pitchers rating in the green or near-green or in the red or near-red than towards the league-average 50 mark. The six who finished fully in green plus or better territory were Hunter Greene, MacKenzie Gore, Caden Lemons (albeit over only 10 batters faced), Hans Crouse, Blayne Enlow, and Matt Tabor. Organizations were mostly very conservative with their post-draft assignments of their 2017 prep arms, as only Greene and late-season teammate Jacob Heatherly pitched above the two transitional rookie leagues (Arizona League, Gulf Coast League).
.
Prep Pitchers Signed from Rounds 11 Through 40, Overall Ratings Plotted Chronologically by Draft Order
The pitchers to watch in 2018 from this group would seem to be Harold Cortijo of the Yankees (Round 14) and Matt Givin of the Marlins (Round 20), each of whom finished fully in the green and did so over a larger sample of work.
.
Complete Ratings of all 2017 Draft Prep Pitcher Signees, Sorted from Highest to Lowest Overall Rating
This first table below features pitchers who earned an Overall Rating of half plus or better. 'R' level corresponds to rookie Arizona League or Gulf Coast League action, and the vast majority of the plate appearances evaluated here happened at those venues. 'R+' level indicates advanced rookie Appalachian League or Pioneer League play.
Third overall pick MacKenzie Gore posted perhaps the most complete set of prep debut ratings of the FaBIO era, falling only 22 percentile points shy of going 12 for 12 in green ratings. Second overall pick Hunter Greene looked to be riding his 4-seamer more than his offspeed arsenal to a 98 Overall Rating over 3 shorter mound stints in the Pioneer League (where he also logged 30 offensive plate appearances). Third-rounder Matt Tabor looked exceptionally strong on an all-around basis across 4 Arizona League outings. Second-rounder Hans Crouse and third-rounder Blayne Enlow make for another pair of preppers who excelled at the K and GB concurrently.
In Ethan Lindow (80 Overall, above) the Phillies may have added yet another under-the-radar southpaw performer to their teeming stable of them.
Cody's brother Cole Bellinger broke even on Overall Rating (51 Overall, below) despite a single digit Batted Ball Rating that was wrecked by louder aerial contact. Again, very few preppers landed within the usually populous Overall Rating window that spans from half plus to half minus.
Lefty Jacob Heatherly (35 Overall, above) was nearly plus against RHB thanks to a strong combo of strike-throwing and groundballing, but extreme CTL/K struggles against the less often encountered LHB pulled his Overall Rating down to half minus territory. Twenty-first overall pick DL Hall (32 Overall) also landed in half minus territory while posting one of the more irregular batted ball profiles around some definite control struggles.
The next table features a plethora of prep debutants who posted an Overall Rating below half minus, and makes for one where Pirates fans should not be overly excited to find first-rounder Shane Baz and second-rounder Steven Jennings.
Among other early round selections to disappoint were Matt Sauer, Seth Corry, Sam Keating, Landon Leach, Brendan Murphy, James Marinan, Jeremiah Estrada, and John Swanda. Whereas a year ago the Mets signed 5 prep arms with none posting an Overall Rating above 43, this time around they inked 6 with none scoring higher than 30 on Overall Rating.
.
Top Post-Draft Debuts Among 2017 to 2013 Prep Pitcher Signees, Sorted by Overall Rating
Kolby Allard was the lone prep debutant since 2013 to beat MacKenzie Gore on Overall Rating, and Allard's mark was surely boosted by an unusual confluence of IFFB generation and LD avoidance within a tiny sample of batted balls.
In perusing through the names listed in these tables and considering where each prospect stands today, most would agree that the higher the prospect rates in their pro debut the better their nearer term fortunes should be.
And that would stand to ring even truer the more credible to sustainable the batted profile seems.
.
Post-Draft Debuts of Prep Pitchers Signed from Rounds One through Three from 2017 to 2013, Sorted from Highest to Lowest Overall Rating
Filtering down to selections from the first three rounds produces a population that also possessed a stronger scouting pedigree at the time of the draft from which they were inked.
The above group of first three-rounders who went plus or better in the wake of the draft makes for a very strong aggregation of current prospects that would be even stronger had injury not wreaked havoc on a few throwing arms.
Aside from Michael Kopech and perhaps Justus Sheffield or Nick Neidert, the next table featuring debut marks between plus and league-average seems more populated by middle to back of rotation SP prospects.
Of the next ten who debuted between league-average and half minus, only Joey Wentz (who would have landed in the middle of the above table if not for extreme LD allowance) would rank as a stronger MLB SP rotation prospect today and perhaps only Tony Santillan would even be considered a viable MLB SP prospect among the rest.
With perhaps an exception or two, the final table featuring preppers who debuted with a below half plus Overall Rating could well be titled "Bust City" as one circumnavigates through its constituents.
As illogical as it might sound, most of the pitchers who made the above table may have already had their hopes of becoming a viable MLB SP dashed only a few dozen batters into their professional careers. Altogether I am becoming increasingly convinced that, in this modern era of travel baseball and showcase circuits, when a top prep draft prospect fails to display sound pitching fundamentals in these FaBIO-centric realms during their professional debuts, we should be very skeptical that they will amount to much in the way of an MLB SP should such an opportunity ever arise. And if you buy at least somewhat into what the above table seems to communicate, then scroll back up to the third/final 2017 results table and reconsider your own evaluations of the top draft prospects that appear there.
.
Exit Poll
Given that MacKenzie Gore stands to walk away with the award for top professional debut among the 2017 prep pitcher draft class, I will instead ask you to decide who had the second most impressive debut within that cohort among four choices.
.
