The Bill James Handbook lists Range Factor, which is the number of Successful Chances (Putouts plus Assists) times nine divided by the number of Defensive Innings Played. Does this statistic correlate with the TPB range ratings? I picked a couple of the more important defensive positions and compared the 2007 Range Factors for starters with the TPB range ratings from the 2007 TPB Statistics Book. Graphs for shortstops and center fielders are below.
Shortstops show a bit of correlation. It’s no surprise to me that Furcal & Vizquel are highly rated by both measurements. I’m surprised to see that Reyes has such a low Range Factor.
Center fielders are all over the place. Vernon Wells has a Superior TPB rating and the lowest Range Factor!
The red lines are the linear fits to the data. The graphs assume that the TPB ratings are linear, that is, that the difference between VG & SP is the same as between PR & WK. Whether or not that’s the intent, it’s clear that there’s no strong correlation between the Range Factor and the TPB range rating. That could mean that either 1) the two measurements are meant for different purposes, or 2) one or both of the measurements are inaccurate.
I don’t think #1 is likely. Surely each is trying to quantify the ability of a fielder to field balls that are hit in his general direction. Of course, measuring any kind of defensive ability is difficult. (See this discussion of various methods.) Whatever the case, it’s clear that the TPB ratings are not based on Range Factor.