Context is critically important in evaluating relievers. Beyond just the obvious requirement for a reliever to be deployed with a small lead at the end of a game to earn a save, different relievers face all kinds of more subtle differences in the difficulty of their relief appearances in order to earn saves and other good statistics. Pulling from The 2016 Bill James Handbook, here are a few leaderboards that provide a window into some greater context for relievers from 2015 than what saves alone can provide.

Cody Allen finished outside the top 10 of relievers with 34 saves in 2015, but no one came close to his total of seven Tough Saves. A save is considered "tough" if the relief pitcher enters the game with the tying run on base. Many clubs are willing only to bring in their closers at the start of the ninth inning, but the Indians turned to Allen to help them out of many different jams this season, and he delivered.

While many of the best relievers are consistently used as their teams’ closers, some setup men are also among the best relievers in baseball. Dellin Betances of the Yankees is one such example. Batters had just a .510 opponent on-base plus slugging against him, better than all but two closers. Meanwhile, his teammate Andrew Miller finished second and new Yankee Aroldis Chapman finished eighth.

Tough Saves provide a piece of the reality that not all saves are created equal. Another realization of that concept is leverage index, which measures how critical each situation in a game is based on the possible changes in win expectancy. Just because a closer is used at the end of a game does not mean he is used at the most critical point, but because teams tend to rely on closers in close games, the five relievers with the highest average leverage index in 2015 were all closers, at least for part of the season. The leader, Carson Smith, is also the most interesting name for this offseason since he was recently traded to the Red Sox. Similar to the Yankees, the Red Sox appear to have committed a lot of resources to solidifying the back of their bullpen. Everyone is eager to follow the blueprint established by the World Series champion Royals.