Anthony Gose Ranked Well On Lesser Known Defensive Measure

Tigers center fielder Anthony Gose ranked high on Revised Zone Rating Runs Saved statistic
(Photo credit: David Richard, USA Today Sports)

Knowledgeable Detroit Tigers fans who watched the team on a daily basis saw speedy outfielder Anthony Gose covering the vast center field of Comerica Park and considered him an asset to the team defensively.  So, they were perplexed by advanced metrics such as Ultimate Zone Rating (UZR) and Defensive Runs Saved (DRS) which suggested that he cost the Tigers 10-12 runs compared to an average center fielder.  There was however another statistic which was more in line with the observations of fans.

You might have noticed that Gose made 101 Out of Zone plays (OOZ) according to Baseball Information Solutions. This is good for fourth best among major league center fielders.  He did not rank nearly as well on the complementary statistic - Revised Zone Rating (RZR).  He had an RZR of .906 which means that he made 90.6% of the plays in his zone.  That placed him in the bottom third of center fielders.  The two measures together suggest that he had very good range, but was not as reliable turning more routine plays into outs.

There is a common misconception that RZR and OOZ are connected to either DRS and UZR, but they are not.  Whereas DRS and UZR break each position into several zones and treat each sub-zone differently, RZR and OOZ only have one zone for each position.

Some fans have asked whether RZR and OOZ can be translated into runs like the more complex defensive measures.  A few years ago, Statistics Analyst Colin Wyers (who now does his work for the Houston Astros) developed an algorithm which combined RZR and OOZ and translated these numbers into plays made above average (PMAA) and runs saved above average (RSAA). 

Wyers' algorithm has a lot of steps.  If you don't want to see all the math, you can jump to the table at the bottom of the post and look at the PMAA and RSAA columns.  Anyway,  Gose had the following numbers in 2015:

Innings = 1,120

Balls in Zone (BIZ) =  277

In Zone Plays = 251 

RZR = .906

OOZ = 101

First calculate the average RZR for center fielders (proportion of all plays in the zone successfully converted to outs) and consider that to be the expected RZR (EXPRZR) for each player.  From that, calculate the plays made in zone above/below the league average (PIZAA) for each player:

          PIZAA  = In Zone Plays - BIZ*EXPRZR

The average RZR for MLB center fielders in 2015 was about .914.  So, Gose's PIZAA = 251 -  277 x .914 = -2.  Thus, he made an estimated 2 plays in the zone below what would expect from an average center fielder.  

Next, assume that the number of balls hit outside the zone is correlated with the number of innings (a big assumption, but the best we can do given the available data). Then calculate OOZ per inning for all players combined at each position (EXPORATIO).  Compute, for each player, the plays made outside the zone above/below the MLB average (OOZAA):

          OOZAA = Out of Zone Plays - Innings*EXPORATIO

The EXPORATIO for center fielders in 2015 was .069.  So, Gose's OOZA was 101 - 1,120 x .069 = 24.  This means that he made an estimated 24 plays outside the zone above what you would expect from an average center fielder.  

Next, combine plays made inside the zone and plays made outside the zone to get plays made above average (PMAA):

           PMAA = PIZAA + OOZAA

Gose's PMAA was -2 + 24 =22.  So, he made an estimated 22 more plays than would be expected by an average center fielder.  

Some time ago, analyst Chris Dial (now a member of the Board of Directors for the Society for American Baseball Research - aka SABR) estimated that the average play made by a center fielder saves .842 runs.  So, we can estimate the runs saved/cost (RSAA) by  a center fielder as:

          RSAA = .842*PMAA

For Gose, that comes out to RSAA=19.  Thus, he saved the Tigers an estimated 19 runs defensively compared to an average centerfielder.  That is a lot better that the -10 and -12 he netted on UZR and DRS respectively.  

Table 1 below shows the statistics for all MLB center fielders with 900 or more innings in 2015.  You can see that Gose ranked fourth in baseball on RSAA.  The MLB leader was Royals fly catcher Lorenzo Cain (35) followed by Kevin Pillar of the Blue Jays (34).

Is RSAA any better than UZR or DRS or other advanced defensive metrics.  Probably not, but it has the advantage of dividing plays into inside the zone and outside the zone, which is information we don't get from other metrics.  As always, take these numbers with a grain of salt.  It is always preferable to look at multiple metrics and years when dealing with defensive data.  

In this case, the numbers on Gose are all over the place, so this might be one of those times where you need to make a judgement based on your own observation or the observation of others whose scouting instincts you trust.  

Table 1 Center fielder Runs Saved Leaders, 2015

Player	Team	Inn	RZR	OOZ	PIZ AA	OOZ AA	PMAA	RSAA
Lorenzo Cain	KCR	1,173	.942	114	8	34	42	35
Kevin Pillar	TOR	1,236	.954	113	12	28	41	34
Kevin Kiermaier	TBR	1,174	.928	100	5	19	24	20
Anthony Gose	DET	1,120	.906	101	-2	24	22	19
Odubel Herrera	PHI	1,065	.930	90	4	17	21	18
Mookie Betts	BOS	1,157	.935	93	5	14	19	16
A.J. Pollock	ARI	1,303	.924	104	3	15	17	15
Michael Taylor	WSN	802	.948	66	6	11	17	14
Juan Lagares	NYM	999	.916	81	1	13	13	11
Billy Hamilton	CIN	975	.949	69	8	2	10	8
Mike Trout	LAA	1,362	.933	96	7	3	9	8
Michael Bourn	- - -	858	.929	65	3	6	9	8
Carlos Gomez	- - -	959	.910	68	-1	2	1	1
Cameron Maybin	ATL	1,129	.867	90	-13	13	-0	-0
Jacoby Ellsbury	NYY	948	.925	60	2	-5	-3	-3
Austin Jackson	- - -	939	.895	65	-4	1	-4	-3
Dexter Fowler	CHC	1,324	.925	80	3	-11	-8	-7
Adam Jones	BAL	1,168	.918	71	1	-9	-8	-7
Joc Pederson	LAD	1,223	.929	72	3	-12	-9	-7
Charlie Blackmon	COL	1,209	.879	83	-9	0	-9	-7
Adam Eaton	CHW	1,280	.917	77	1	-11	-10	-8
Marcell Ozuna	MIA	924	.891	58	-5	-5	-10	-8
Billy Burns	OAK	1,066	.933	56	5	-17	-12	-10
Angel Pagan	SFG	1,061	.889	50	-6	-23	-29	-24
Andrew McCutchen	PIT	1,374	.913	50	-0	-44	-45	-38

Data source: FanGraphs.com