A Closer Look at the Mariners’ Bullpen, Collectively

Lost amid all the offensive acquisitions and talk of having one of the best starting rotations in the league is the quiet strength of the Mariners, the bullpen. This group has stayed the most consistent between last year and this coming year and should continue to be one of the best bullpens in the league.

Instead of looking at individual relievers, who are susceptible to wild swings in performance, I'd like to take a look at the Mariners bullpen as a group. What were they able to accomplish together and what can we expect from them in 2015.

Last year, Lloyd McClendon relied on an eight-man bullpen for most of the year. That group led the American League in ERA and FIP and had the lowest opposing batting average. They collectively had the second highest swinging strike rate in the league and were third in K-BB%. Once the Mariners got to the seventh with a lead, they were 68-8 last year, a .895 win percentage. WAR is a pretty flawed way to measure a bullpen but the Mariners' relievers were worth 4.5 fWAR in 2014, good for fifth in the AL. By RA9-WAR, they were first in the AL with a cumulative total of 8.9.

If we use FanGraphs' Shutdown and Meltdown metrics, the Mariners fall to ninth in Shutdowns converted with just 115. If we use Shutdown-Meltdown Differential (SD-MD), the Mariners bounce back to seventh. It's hard to say why the Mariners' bullpen accumulated so few Shutdowns. Since the metric uses Win Probability Added as its basis, it could be that the Mariners' eight-man bullpen reduced the amount of chances for individuals to accumulate the +.06 WPA to earn a Shutdown (and the reverse maybe true too).

So how is the bullpen shaping up for 2015?

It's unlikely that McClendon goes with another eight-man bullpen this coming year. With a platoon in right field and a need for a backup middle infielder and backup first baseman, there just isn't room on the roster for an eighth reliever. With six of the eight relievers from last year's group returning, most of the bullpen is already decided. The seventh member of the ‘pen could be Carson Smith, a second lefty, or Erasmo Ramirez. That all depends on how much depth the Mariners can stash down in Tacoma.

Let's see how the Mariners' bullpen compares to the other teams in the AL. Using the depth charts on FanGraphs, I pulled the cumulative ERA, FIP, WAR, and RA9-WAR totals for all of the bullpens in the AL. Here's that data in chart form:

The Mariners currently rank fifth in FIP, fifth in ERA, sixth in WAR, and seventh in RA9-WAR. As currently projected by Steamer, the Mariners have a high- to mid-range bullpen. With the number of relievers still on the market, it's realistic to think that the Mariners could slip lower on that chart as other teams upgrade their bullpens.

However, the depth charts on FanGraphs list between ten and fifteen relievers, many of whom will never see a single inning at the major league level. Some of these depth pieces will see time with their respective teams but I wanted to see how the projections changed if we used just the top projections. I took the top seven projected relievers for each team in the AL and came up with some adjusted cumulative totals.

With these adjusted totals, the Mariners move up to third in FIP, fourth in ERA, fourth in WAR and stay steady at seventh in RA9-WAR. The front line of the Mariners' bullpen looks like one of the best in the league.

Last year, the Mariners enjoyed some incredible luck when it came to avoiding injuries to their relievers. In fact, none of the Mariners' top eight relievers spent any time on the disabled list last year. They can't count on that same kind of injury luck in 2015. Still, barring any major injury trouble, it's nice to see that the Mariners should continue to sport one of the best bullpens in the league.