This post is about using stats of all kinds to tell us a player's true talent level versus telling us what a player did in a single year. Lets start with a traditional stat and let's use 3 seasons Hypothetical Joe Smith played for the same team from 2012 to 2014 and will continue to play for that team in 2015. He posted an OPS of .840 in 2012, .719 in 2013, and .855 in 2014. We'd look at that and say Joe Smith is probably a .830-.840 OPS guy more or less right? That's probably his true talent level, roughly. But does that mean they .719 year didn't happen? Does that mean that in 2013 he didn't actually have a .719 OPS? When our goal is to look at how Joe Smith played in 2013 compared to his peers, do we care about his true talent level in that discussion? Let's take hypothetical pitcher Jim Johnson,. Same years, same team situation. He posts an ERA of 3.25, then 4.37, then 3.18. His true talent level is probably around 3.25-.3.35 ERA. But if we talk about the year he had a 4.37 ERA, regardless of whether or not his true talent level is 4.37 or not, it still happened. That's still what he did that year. We've known this for a long time how to figure out what the true talent level is in these kind of stats but we also clearly accepted that the year to year data told us what the player did that year regardless of whether or not he was really that good or that bad. Now, just because the SABR community reminded us of what we know when just traditional stats were around, that stats are best used with more info to determine a players true talent, that doesn't mean we don't do the same thing with new metrics that we did with traditional stats in the above two scenarios. That doesn't mean we can't use stats compiled in a year, traditional and newer, when talking about how a player did in that year compared to others regardless of whether or not it's his true talent level. His true talent level isn't relevant when discussing how a player did in one individual year. So, if a guy had a WAR of 5.0 in 2012, 2.7 in 2013, and 5.1 in 2014, his true talent is around probably around 5.0, but in 2013 he WAS a 2.7. That still happened. He under-performed his true talent level in 2013. Same thing if someone had a 6.5 UZR, a 1.7 UZR and a 6.2 UZR. He's probably a 6.1 or so UZR guy but that one year, he WAS a 1.7. If the conversation is about what kind of talent does this player really have, look at the last three year with more emphasis on the more recent seasons (do that with traditional stats as well as newer stats), but if asking how a player performed during a single year, you can look at the stats for that year (traditional and newer stats) and say, regardless of true talent level, THIS is what he did that year.