In reliever-rich AL East, depth may prove the difference in the bullpens

Previously, we took a look at the ongoing AL East bullpens arms race, with nearly every team in the division stacked from the top to bottom with good relievers. They follow in the footsteps left by the Kansas City Royals who, over the last two seasons, exploited this inefficiency around baseball to differentiate themselves from the leage. But with every team now building up their bullpens with flamethrowers, this inefficiency might not exist anymore, particularly in the East.

Due to the growing number of teams that can seemingly strut out a "Big 3" relief corps, the next way for teams to separate themselves from the pack would be with depth. Relievers, by nature, are fickle; nobody expected Wade Davis to become what Wade Davis is today. Nobody expected Koji Uehara to Koji Uehara quite so hard in 2013, when he went on a Rivera-esque streak of dominance. And just as quickly, a formerly dominant reliever can become a putz of a pitcher. Just ask Eric Gagne what the hell happened in 2007 after he became a member of the Red Sox (Side note: How insane is that he won the Cy Young Award in 2003? Imagine how quickly Twitter would burn down if a reliever won the award today).

Dave Dombrowski probably heard all of the naysayers talk about his failures to put together a competent bullpen with the Tigers and went out of his way to put together a group that, on paper, looks to be a major strength for the team. With Craig Kimbrel, Koji Uehara (who is far from a sure thing given his age), Carson Smith and Junichi Tazawa, the Red Sox at least appear to have a strong back end of the bullpen. But that matters slightly less when considering their competition also has Aroldis Chapman, Dellin Betances, Andrew Miller, Zach Britton, Darren O'Day, Wade Davis, Kelvin Herrera, etc, etc, etc. What was once an abnormal strength for the Royals has, on paper, become a nearly necessary element of putting together a team that can compete for a spot in the playoffs.

But, inevitably, some pitchers are going to get injured, and others will struggle to live up to expectations or past successes. When that happens, the teams that are able to use their depth to plug in that hole with a similar or better pitcher will separate themselves from the pack of teams that bring stacked bullpens to the table to start the season.

The Royals experienced this first-hand last year with one of their best pitchers. When Greg Holland went down for the remainder of the season due to Tommy John surgery, the team needed to fill those shoes with someone competent. The moved Wade Davis into the role, moving Kelvin Herrera into Davis' role and using their depth in the form of Ryan Madson, Franklin Morales and Luke Hochevar to cover the lost innings. Morales provides the perfect example of the crapshoot science that is building bullpens. Morales came to the Royals after spending a year with the Rockies as a starter, and a pretty bad one at that. It had been two years since Morales put together a solid season out of the bullpen, let alone as a pitcher. Yet he emerged as a dependable reliever for Kansas City and helped solidify a bullpen that saw a big loss at the tail end of the season.

Taking a look at the depth in the Red Sox relief corps, Joe Kelly, according to Steamer, projects as the team's best reliever next season after Tazawa. Kelly, however, will receive another opportunity to start after a successful stint in the rotation at the tail end of last season. After that, there's is Robbie Ross, Matt Barnes and Tommy Layne, otherwise known as the replacement-level relief corps. Given their track records, it's hard to paint any of the three pitchers as more than what they have been in their careers so far, although Barnes' track record as a first-round pick with good stuff suggests a potentially higher ceiling out of the pen than either Ross or Layne.

Looking at the minor leagues and prospect rankings for relievers is usually not a great practice for finding that next great closer given that most (with Kimbrel as an exception) don't come up through the farm systems as relievers or closers. Uehara started and relieved for the Orioles when he came from Japan. Chapman was expected to start when he signed with the Reds. Betances was one of the Yankees' brighter starting pitching prospects. Miller was a first-round bust of a starting pitcher when the Red Sox traded for him from the Marlins. Tazawa came up as a starter through the minors. And on, and on, and on.

Pat Light, armed with a bullet of a fastball, is perhaps the most interesting name the Sox have in the system when it comes to players that have already made the transition. In 30 innings of relief work in Portland last year, Light produced a 2.43 with better than a strikeout per inning. But given that Light doesn't have any experience at the major league level, has had issues with command in the past, and couldn't even smoothly transition to Pawtucket in 2015, marking him off as a dependable bullpen relief option from the get go would be a stretch, similar to how some thought Barnes could make an easy transition last year out of spring training.

It's really easy to nitpick relievers, and I know that I've spent the last three paragraphs basically writing off everyone in the Red Sox bullpen not named Kimbrel, Smith, Uehara or Tazawa, but that's kind of the point. Sometimes the best contributions out of relievers who nobody expected to make a big jump in performance or be really successful coming out of the bullpen. Mariano Rivera made 10 starts (!!!) in his rookie season before become a full-time reliever. Constructing a bullpen is an imperfect, unpredictable science, but with so many teams building über bullpens, the pitchers that come after the big-ticket relievers will differentiate the great bullpens, from the simply good.