WAR for Pirates prospects

I thought it would be cool to see Wins Above Replacement (WAR) numbers for some of the Pirates’ top prospects. So I started doing some calculating. For offense, I used wRAA from FanGraphs. The only decent measure of minor league defense that I am aware of is TotalZone over at Minor League Splits, developed by Sean Smith of Baseball Projection. Then I simply added positional and replacement adjustments, and added everything up. Take these numbers with a grain of salt, as they are not going to be as accurate as major league stats. First of all, wRAA is not park adjusted. Also, TotalZone does not include batted ball location, as UZR and other advanced metrics do. It is a great tool when we have insufficient data, though (such as in the minor leagues). Finally, other than Jose Tabata, none of these players has reached Triple-A yet. Determining pitcher WAR is kind of a pain, so I chose not to bother. Without further ado, here is estimated 2009 WAR for seven of the Pirates’ top position player prospects. I also computed WAR per 600 plate appearances, to show what each player would have accumulated in an average full season. (Note: I estimated Tony Sanchez’s defense to be about +5 per 150 games, as catcher defense is difficult to measure.)

 

2009	PA	Offense	Defense	Pos.	Rep.	WAR	WAR/600
Pedro Alvarez	542	31.1	-4.0	2.3	18.1	4.7	5.3
Jose Tabata	402	4.7	-12.0	-2.0	13.4	0.4	0.6
Tony Sanchez	215	16.9	1.8	4.5	7.2	3.0	8.5
Chase D’Arnaud	508	28.9	12.0	5.0	16.9	6.3	7.4
Starling Marte	256	11.3	17.0	-0.6	8.5	3.6	8.5
Robbie Grossman	535	11.7	21.0	-0.3	17.8	5.0	5.6
Gorkys Hernandez	602	-7.4	14.0	2.5	20.1	2.9	2.9

 

I was disappointed by Tabata’s numbers, particularly his defense. It is clear that he belongs in a corner outfield spot. The rest of the list looks great, though. Marte managed to be worth 17 runs above average on defense, as he and Sanchez each put up MVP-type production in about half a season. D’Arnaud did the same over the entire year. Alvarez and Grossman put up All-Star caliber seasons, while Hernandez’s elite defense allowed him to be a slightly above average player.

Most of these players have a ways to go before reaching Pittsburgh, so it is important to temper expectations. But it is encouraging to see these impressive performances.