'Here are his F2O% numbers by position compared to the rest of baseball for 2016. (And before anyone responds, F2O% is NOT fielding percentage): CF - Santana 49%, league average 53%. RF - Santana 41%, league average 50%. LF - Santana 40%, league average 46%. SS - Santana 100%, league average 89%. 3B - Santana 83%, league average 87% 2B - Santana null%, league average 92% (1 game, 0 balls hit to his zone)' So, I dove into this stat I never heard of, cause hey. I like learning new things. Here is what I found: F20% means Field To Out ratio. So, like fielding % really, with a fancy name. It is part of an equation to form a bigger stat to be looked at (the other part being Revised Zone Rating which attempts to measure range) That bigger stat that is formed is only one part (z-outs) of three parts (z-outs, z-range and z-fielding) to create an even larger stat: zdefense. zdefense is fairly new and as far as I can tell, isn't anywhere near accepted. I can't find it, honestly, on the Fangraphs site other than the primer talking about it. It's one guys recent attempt at creating something like his own UZR (with a different name but to do the same overall thing by different measures) in an overall attempt to create something like his own WAR (Which he calls PEACE: Player Evaluator and Calculated Expectancy). In any event, F2O% by itself doesn't tell you much of anything. Even combined with RZR it barely tells you anything. I have never seen anyone look at someone's F2O% by itself to determine overall fielding ability. Never heard it quoted or mentioned when talking defense anywhere but here, by one person. It looks like it's akin to determining OBP by looking at only HBP. I will say, I found the research into this interesting. Even though I wouldn't feel comfortable using F20% to determine a players defensive prowess, I'd like to thank Doomtints for using the partial stat and making me curious enough to look it up. .