25 February 2016

Why the Projection Systems Can't Get Bryce Harper Right

"History will little note, nor long remember, what we say here." --President Abraham Lincoln at Gettysburg battlefield, considered the worst prediction in human history.


The futility of predicting the future in baseball has been amply documented and only weakly lamented. Bless their hearts, the various Sabermetric websites continue to offer the old college try, annually tweaking their systems to finer and finer levels of mediocrity. Fangraphs, Bill James, Baseball Prospectus, Tom Tango and The Hardball Times all provide projections whose mathematical formulas do a 5% better job than you would making educated guesses.

As I've mentioned before, understanding a few simple rules will give you all the tools you need to pull even with, or even out-guess, the projections. The reason is that these systems are prisoners of their calculations, whereas you know something or two about the players.

Take Bryce Harper, who flummoxes PECOTA, ZIPS, Steamer, Marcel, Bill James and all the rest. Harper was a young phenom who flashed wads of unrefined brilliance in his first three seasons but also got himself injured with regularity because of his over-exuberance. Then last year, having learned how to stay on the field and harness his innate power, he blasted 42 homers and got aboard safely at a 46% clip, en route to the MVP.

What the projections systems see is a good player who scuffled along for three seasons batting .270 with 20 home runs before out-performing himself in 2015. Consequently, they are regressing him to the mean. Here is PECOTA's projection of Harper:

2015 (Actual)
22
.386
11.2
2016 (Projected)
23
.313
5.1
2017 (Projected)
24
.322
5.5
(That's age, True Average and WAR listed in the three columns above.)

That's generally the way to treat players, but this is Bryce Freakin' Harper. When it crunches the numbers and spits out its projection, PECOTA doesn't know Bryce Harper from Valerie Harper. It's never seen this prodigy play.  It thinks he's just a guy whose pants were on fire last season.

You know better. You know that's the Harper we've been waiting for, and that putting it all together at 22 makes him a superstar not in spite of three previous seasons of .270 and 20 home runs but because of what we saw during them. 

I'll bet my Pope Francis Fan Club membership that Harper posts a TAv north of .350 this season and, if he stays upright, hands at least another eight wins to the Nationals. It may not work out that way, but that's what PECOTA would say is a reasonable 50% percentile projection if it had the ability to discern the man behind the statistics.

It doesn't, as none of the projections systems do, which is one of the reasons they aren't of much use.

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