Jonathan Daniel/Getty Images
You should recognize most of the stats referenced in the pages ahead, but you're going to come across some lesser-known stats as well. In particular, keep an eye out for the following.
wOBA: This is Weighted On-Base Average, and the best way to think of it is as a superior version of OPS. You can read all about it on FanGraphs and in a recent article of mine, but you can get by knowing that a .320 wOBA is about average and a .400 wOBA is elite.
ISO: This is Isolated Power, and it's pretty much just what it sounds like. It's a stat that measures how good a hitter is at hitting for extra bases. FanGraphs has the full rundown.
UBR: This is Ultimate Base Running. Imagine a stat that scores runners based on the decisions they make on the basepaths, and you have UBR. FanGraphs has the rundown.
UZR: This is Ultimate Zone Rating, and it's a stat that uses play-by-play data to assign fielders run values above or below average (which is zero). FanGraphs has the rundown.
DRS: This is Defensive Runs Saved. It's similar to UZR in that it's a defensive stat that assigns fielders a run value above or below zero. Having both stats to turn to helps one get a clear picture of how good or poor a player's defense is. FanGraphs has the rundown.
FIP, xFIP and SIERA: These are ERA estimators. You don't need to know the specifics, but just know that these stats are designed to judge pitchers in light of things they can actually control (strikeouts, walks, home runs, etc.).
As for how the list is ordered, I considered how players performed in 2012 and their track records in recent seasons. Track records were tricky when it came to relief pitchers, as relatively few have track records as elite players.
I was forced to make a compromise with relievers: No one-year wonders. That means no Fernando Rodney and no Aroldis Chapman. Chapman was the easier of the two to bar from the list because we don't know if he can be as good as a starter as he was as a reliever.
The other major thing I took into consideration was health. Generally speaking, players coming off injuries are not ranked as high as they would be if they were otherwise healthy.
Now then, let's get to it.