I’ve been talking with a former BPer who now works in a major league front office about minor league equivalences — specifically, the PECOTA projection for Thomas Hickman, an outfielder in the Marlins system who had a good debut for the Marlins’ Gulf Coast League affiliate last season. PECOTA forecasts a .414 major league equivalent slugging average for Hickman this year, which might seem generous for a relatively unheralded 19-year-old.
It’s fairly easy to see how PECOTA comes to this conclusion. Clay’s numbers say that Hickman posted a .395 equivalent slugging average (EqSLG) last year, and PECOTA simply thinks that the natural growth that a 19-year-old can be expected to experience will outweigh any regression to the mean, causing his EqSLG to rise by about 20 points. How the DTs had him at a .395 EqSLG is another question, considering that his raw, untranslated slugging average was .411, until you look at the fact that the entire GCL Marlins team hit just .227/.297/.299 at home; Hickman was a couple of standard deviations above the norm.
The bigger question, though — even assuming that PECOTA and the DTs did their job perfectly — is whether Hickman would actually post a .414 EqSLG in the majors next year if the Marlins said “here kid, the job is yours” on Opening Day and never looked back. This doesn’t just apply to Hickman, of course, but to any minor leaguer who is far enough down the food chain. Wouldn’t the player struggle if he was promoted to the majors (or for that matter, to an advanced league like Triple-A) so prematurely?
Both PECOTA and the DTs are formed from empirical data, and empirically, players just about never go straight from the Gulf Coast League to the majors. So the way that the DTs work is through an iterative process. There are plenty of players that go from Double-A or Triple-A to the majors, so the DTs look at how those players have progressed, then compares how players performed at Double-A and full-season A-Ball, then compares them at full-season A-Ball and short-season A-Ball, and so forth, until you get all the way down to the rookie leagues. This process is done very, very carefully, but even if it’s performed optimally, you still have a process analogous to what happens when a document gets faxed back and forth several times, where there’s a lot of blurring around the edges.
In real life, major league organizations probably do promote their players in a reasonably optimal fashion, accounting for both their physical/statistical attributes and perhaps their psychological makeups. Since the DTs are based on this real life data, they wind up adopting this assumption — that a player’s development is handled in a more-or-less competent way. If a player like Hickman was promoted too aggressively, giving him far too much learning to do and perhaps making him feel like a failure, or too conservatively, leaving him bored and frustrated and unable to hone his skills against better competition, there is no guarantee that he’d match his PECOTA.
In other words, what you probably have is something like this:
These numbers are wild flippin’ guesses, but the point is that Hickman might be penalized if his promotion was handled inappropriately. He might also get a very small bonus over his PECOTA projection if his promotion was handled optimally, since some minor leaguers in the historical data set probably haven’t been.
Of course, we don’t know that Greensboro, say, is the best destination for Hickman. He could be one of those special kids that would be more helped than harmed by a more aggressive promotion, or one of those kids who benefits from really mastering a level before he moves on. We also don’t know what this means for his long-term development. Maybe he’d struggle if promoted straight to Triple-A next year but would wind up benefiting in the long run, or maybe he’d end up with some permanent psychological scars and some lost development time that he’d never get back.
What we could do is run a separate PECOTA projection for Hickman at every level, sort of like I’ve tried to do above, but even that doesn’t remove the ambiguity completely: can a major league equivalency really be called a major league equivalancy if a player couldn’t actually produce those numbers in the major leagues? Perhaps for very young players, MLEs need to be thought of more as sort of the track that a player is on versus the literal truth — what we might call Major League Pace (MLP). IQ scores work sort of like this, since they’re adjusted for age. An 8-year-old with an IQ of 140 would probably not beat an adult with an IQ of 120 at a game of chess, but he’d be “on pace” to do so when he was an adult himself.
You might even say that Hickman’s projection in, say, 2011 (which is also very good) is arguably more reliable than his projection for 2007, since by that point essentially all of his comparables had advanced to majors, or to leagues like Triple-A and Double-A that allow for easier apples-to-apples comparison with the majors. PECOTA thinks that David Wright, for example, is a good comparable for Hickman. Wright has obviously done fine for himself against major league competition — but we don’t know what he would have done if he’d tried to face major leaguers at age 19.