Behind the Cubs and the Rays, the San Francisco Giants rank third in overall left field UZR from 2002-2010. That's right. Guys like Pat Burrell, Moises Alou, Pedro Feliz, and Barry Bonds, among several others, have combined for a total of 63.7 UZR. That just doesn't seem to make sense. Sure, it's plausible that the Giants could have a decent positive rating in left field. But to be third in the majors, right behind the Rays -- who have had defensive god Carl Crawford log almost 10,000 innings at the position since 2002? I doubt it. I'm inclined to believe that UZR is grossly overestimating the Giants' defensive skills in left, as well as that of the Cubs (Alfonso Soriano, Moises Alou, etc.).
So I crunched a few numbers, and it seems the Giants have a significant home/road split for their left fielders.
Here's a chart of the home/road UZR splits of every Giants LF since 2002 (min. 250 innings):
Before we get too far, I'll leave this here.
It's very common for players to have a better home UZR than road UZR. Also, it's very common to see randomness in this data, even if it's a large sample size. But the difference here seems to be significant. Perhaps it's just randomness swaying the data, perhaps not. Only time will tell.
Also, unless I'm mistaken, UZR changed it's park factor in 2010, so we should see a difference in this data in the future. Again, only time will tell.
Still, if you look at all of these left-fielders, they all had positive UZR. Eight of the 11 in the sample had a better home UZR than road UZR.
What's causing all of this? Probably a number of factors -- including a flaw in the park factor, natural randomness, etc.
Whatever it is, I think UZR in general has overestimated the Giants' LF defense, and it seems to be occurring in its estimation of a players' range while playing at home. Fan scouting reports seem to indicate this as well, telling us that the Giants' LF defense has not been as good as UZR would indicate.
Lastly, this seems to defy natural defensive aging curves. Players typically peak defensively at ages 22-25. This sample of Giants left-fielders comprises several guys in their mid-to-late 30s, posting decent UZRs.
If you look at the Cubs, their UZR data for left field also seems very flawed. Look at the home/road UZR splits from Moises Alou in 2003 and 2004. Quite significant.
Anyway, just thought this was interesting...interpret this data as you wish.
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