Early Trends in Bullpen Usage

The 2014 White Sox bullpen has had a revolving door since the beginning of the season. Nate Jones, who came into this year considered to be one of the closer candidates, was the first casualty as he was added to the 60-day disabled list with a hip injury early in April. Lindstrom followed suit and was placed on the disabled list with an ankle injury that requires surgery.  He will be out at least three months.  As a result, Robin Ventura and his coaching staff have mixed and matched with the remaining relievers, including some pulled from the waiver wire and the minors.

Most individuals who subscribe to advanced metrics would agree that your best relief pitcher should pitch in those situations upon which the game hinges the most (i.e. situations when the leverage is high).  By that logic it would make sense for your relief ace to pitch in the eighth inning of a tie game with the bases loaded and no outs and not so much in the same base-out situation in the fourth inning.  Below is a table that shows the average leverage when they enter the game for each White Sox reliever, or gmLI.  I also included FIP and ERA so we can see how their leverage compares to their performance.

  Data Courtesy of Fangraphs.com

Data Courtesy of Fangraphs.com

Lindstrom tops this list, which shouldn't come as a surprise because of his established role as the team's closer.  Save situations by definition tend to be high leverage situations.

While Lindstrom and Petricka seem to be ideal candidates for high leverage situations given their 3.32 and 1.57 ERAs respectively, their peripherals tell a different story.  Both Petricka and Lindstrom walk nearly as many batters as they strike out and this is also reflected in their FIPs.  Interestingly, Maikel Cleto ranks third in terms of highest leverage when entering the game.  Before this season he had only pitched 15.2 innings in the majors and had essentially no success.  Despite his tantalizing fastball, that trend continued this year until he was designated for assignment.

Downs, Putnam and Belasario are sent into the game when the situation is lower in leverage, generally.  Ventura's usage pattern for Downs is about what you would expect from a lefty specialist.  Downs has eleven appearances in high leverage situations and eleven appearances in low leverage situations.  This is because, as a lefty specialist, Downs is often brought in to face one left-handed batter late in the game when there are men on base.  He also often enters the game in mop up (low leverage) situations where his platoon split isn't as crucial to the outcome of the game.

Belasario and Putnam fall to the bottom of the White Sox leverage leaderboards, which is puzzling given their performances of late.  Belasario's overall numbers aren't impressive because of his horrid start to the season that saw him rack up an ERA of 6.32 over the first month of the season.  However, his ERA in May is 3.32 and he has boosted his strikeout rate by 7.9% to a healthy 23.1% this month.  Putnam has also pitched well since being called up from Charlotte in April.  While Putnam is not as good as his 1.64 ERA suggests, its not all smoke and mirrors.  Putnam is striking out almost 20% of the batters he faces while walking only 8.6%.  His split finger pitch has really been working so far this year, which has been the catalyst for his success.  Of the 25 qualified relievers who throw a split finger, Putnam ranks fourth (4.35 wSF/C) by pitch type linear weights.  Belasario is actually second on that same list (7.80 wSF/C).

Jones and Lindstrom are both going to be out for quite some time, if not the whole season.  Therefore it's time to take a long, hard look at just how the bullpen has been used and what would be optimal going forward.  Frankly, even if Lindstrom were healthy this conversation would still be necessary as the declining trend in his peripherals over the last three years makes him no longer qualified for regular high leverage relief duty.  

At this point, Putnam and Belasario should be given a shot in higher leverage situations. Belasario has already appeared three times in save situations since Lindstrom's injury.

While Webb and Petricka have both shown in spurts that they have the potential to become competent major league relievers at some point in the future, they both are due for regression based on their peripherals.  

Javy Guerra and Scott Carroll, who I have not mentioned thus far because they both only have pitched so few innings in relief this season should slot nicely into most of the low leverage situations that arise.  However, I wouldn't count on either spending a lot of time on the roster as those last two bullpen spots will see a lot of movement unless either pitches well.

One final note that I found interesting when looking through data for the White Sox relievers was the average outs per game in relief for the team as a whole.  Last year, there were some complaints about Robin being a little trigger happy when it came to bringing in new relievers.  The White Sox averaged exactly three outs per game in relief in 2013.  The number has increased to 3.4 this season with 3.2 being the average league-wide for both seasons.  Maybe Robin is learning something from Coop after all.

*All of the data in this article comes from Fangraphs.com and Baseball-Reference.com.  All early season articles about relievers are subject to the limitations of small sample size and this article is no exception.

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