Any manager will tell you, a bullpen is a key component to any team's success. Without reliable relievers at a skipper's disposal, much can go awry during the course of a full season.
Starting pitchers can be suspect to injury for pitching too long because a bullpen can't be depended on (just ask Kerry Wood and Mark Prior about that). Or, at the very least, a starting pitcher who is on the mound too long can start to lose effectiveness, potentially shifting momentum over the course of a game.
In 2012, the Cincinnati Reds (2.65) and Atlanta Braves (2.76) had the best bullpen ERA in the MLB. The Reds' bullpen also served up the fewest amount of home runs last season, surrendering just 33 long balls.
So, with Opening Day less than a week away, who's bullpen looks to be the strongest?
A strong bullpen is not solely dependent on the quality of the closer. The depth of the bullpen is also a key factor in determining the top relief cores in the game.
Here are the Top 10 Bullpens, heading into the 2013 regular season.