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Almost Not Premature Stat Report on the Arizona Fall League

Over the past two weeks, the author has published an entirely premature statistical report and then a slightly less premature one of those for the Arizona Fall League — not necessarily because such a thing is of great utility to prospect analysis, but more because, for those of us not currently present in the Greater Phoenix area, it’s one of the few ways to participate in that very compelling league. Moreover, it can serve as a pretense upon which to discuss participants in that league, not unlike Atlanta’s Thomas La Stella.

What follows, then — sans both apology and expertise — is the third edition of this site’s weekly AFL statistical report.

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Almost Not Premature SCOUT Leaderboard: AFL Hitters
Below is the current SCOUT batting leaderboard for all Arizona Fall League hitters. SCOUT+ combines regressed home-run, walk, and strikeout rates in a FIP-like equation to produce a result not unlike wRC+, where 100 is league average and above 100 is above average. Note that xHR%, xBB%, and xK% stand for expected home run, walk, and strikeout rate, respectively.

Player MLB Age PA HR BB K xHR% xBB% xK% SCOUT+
Thomas La Stella Braves 24 32 0 11 0 1.3% 17.5% 10.2% 138
Matt Skole Nationals 23 24 2 8 3 2.6% 15.8% 18.1% 132
Colin Moran Marlins 20 36 0 9 2 1.3% 15.5% 12.1% 128
Kris Bryant Cubs 21 33 4 4 7 3.7% 11.6% 21.5% 126
Michael Ohlman Orioles 22 17 1 6 2 2.1% 14.8% 19.0% 121
Jared Mitchell White Sox 24 24 1 5 2 2.0% 13.3% 16.5% 121
Addison Russell Athletics 19 33 1 5 3 1.9% 12.4% 14.9% 120
Mitchell Haniger Brewers 22 45 2 7 8 2.4% 13.0% 18.8% 120
Camden Maron Mets 22 27 0 8 3 1.4% 15.5% 17.0% 119
Pratt Maynard Dodgers 23 11 1 3 0 2.1% 12.9% 17.9% 118

Almost Not Premature SCOUT Leaderboard: AFL Pitchers
Below is the current SCOUT pitching leaderboard for the AFL. SCOUT- combines regressed strikeout and walk rates in a kwERA-like equation to produce a number not unlike ERA-, where 100 is league average and below 100 is better than average. Note that xK% and xBB% stand for expected strikeout and walk rate, respectively.

Player MLB Age G GS IP TBF K BB xK% xBB% SCOUT-
Nick Wittgren Marlins 22 4 0 4.1 15 9 0 30.1% 10.4% 80
Dominic Leone Mariners 21 4 0 5.1 20 8 1 27.1% 10.7% 87
Bo Schultz D-backs 27 3 3 13.1 57 15 4 25.5% 9.9% 89
Matt Purke Nationals 22 2 2 7.0 27 9 2 26.3% 10.8% 89
Jonas Dufek Astros 25 4 0 5.0 18 7 1 26.3% 10.8% 89
Samuel Solis Nationals 24 3 3 12.2 52 14 4 25.6% 10.3% 90
Ryan Harvey Rangers 22 3 0 3.1 13 6 2 26.4% 11.7% 91
Zachary Thornton Pirates 25 5 0 6.1 24 7 0 24.4% 9.8% 91
Alex Meyer Twins 23 3 3 8.0 31 9 2 25.1% 10.5% 91
Cam Bedrosian Angels 21 3 0 3.2 16 6 1 25.5% 10.9% 91

Regarding Thomas La Stella
Since last week’s edition of the batting leaderboard, Atlanta infield prospect Thomas La Stella has recorded seven walks in 18 plate appearances — all this while striking out zero times. For La Stella to control the plate so well isn’t an entirely suprising development. He posted walk and strikeout rates of 11.5% and 10.5%, respectively, in 323 PAs at Double-A Mississippi. He’s posted similarly excellent rates at other levels, previously.

If one takes for granted his plate discipline and what appears to be below-average second-base defense*, then projecting La Stella as a major-leaguer becomes a matter mostly of targeting his home-run rate (HRC%) on contact and BABIP.

*Note: the author isn’t suggesting that one ought, necessarily, to take either of these for granted. For the sake of the minor experiment below, however, that’s what’s happening.

Below are four possibilities for a major-league version of La Stella, if one controls for everything but HRC% and BABIP. The walk and strikeout rates included here are those projected by Steamer for 2014. The defensive constant presupposes either a -5 defender at second base (Dan Uggla, basically) or a +5 defender in left field (i.e. another destination for defensive misfits).

Line PA BB% K% HRC% BABIP Fld+Pos HR AVG OBP SLG Off Def WAR
1 550 7.3% 10.2% 1.5% .280 -2.5 7 .260 .319 .360 -6 -3 1.1
2 550 7.3% 10.2% 2.5% .280 -2.5 11 .267 .325 .396 0 -3 1.7
3 550 7.3% 10.2% 1.5% .300 -2.5 7 .278 .335 .378 0 -3 1.7
4 550 7.3% 10.2% 2.5% .300 -2.5 11 .284 .341 .413 6 -3 2.4

Line 1 represents La Stella’s 2014 line according to Steamer, more or less. A 1.5% HRC is what La Stella recorded in 2013 at Mississippi, as well. Line 2 features 2.5% HRC, i.e. what La Stella has posted over the entirety of his minor-league career. It wouldn’t be surprising, necessarily, for La Stella to hit for more power, either, as he advances toward complete physical maturity. Line 3 features La Stella with his Steamer home-run projection, but with a major-league average BABIP. Not an impossibility, that. Finally, Line 4 is an example of La Stella recording the more productive versions of his HRC% and BABIP. It’s probably hard to get much more reasonably optimistic than this final example, in terms of La Stella’s true talent.