05 April 2018

Your Best Reliever Sometimes Should Not Close Games

On April 3, Buck Showalter sat down a tired Mike Wright Jr. at the end of the fifth inning.  His night ended at 82 pitches, which was nine more than his last game in Spring Training.  It felt like an early hook and that maybe he could stretch to a couple batters more to provide some cover for a bullpen that has been used heavily the previous couple days.

At the conclusion of the fifth, Wright had covered 20 batters and was about to enter the heart of the lineup for the third time.  In his former incarnations as a starting pitcher, the third time through was typically rough.  Well, all times through were rough, but it got worse that third time.  In his last season as a starter (2016), opponents would hit him in the low 800 OPS range, but that would jump to over 1000 OPS that third time through.  He walked a lot of batters, struck out few, and was hit hard.  The idea since then has been a transition over to a sinker/slider pitcher would help him get deeper into games by changing looks and keeping the ball on the ground.

That was not happening that night, Wright has trouble placing his sinker with it often hitting the glove a foot or more out of the zone.  This led him to rely more on his four seam fastball and slider/curve offerings.  The expectation was that this pairing got him through the order those first two times and he was bound to suffer that third time out there even though his pitch count left some room for another batter or two.  It was an ideal time for him to go.

Added to this, the Orioles had regained the lead and were up 4-3 going into the bottom of the sixth inning.  So traditionally, the idea would be to send out Wright again and see what happens.  As noted above, we should know better than that.  Slightly less traditionally, the idea would be that the sixth inning falls outside of the seventh-eighth-ninth holy reliever Save time and the proper reliever to send in would be your fourth righty or second lefty non-closer into the breach to stop the opposition.  However, we know better than that now.  We actually have known better for a while.

In 2002, Tom Tango (who is now MLBAM's "data architect") came up with the concept of leverage index.  You see, we have a whole lot of information about baseball over the years.  We know what has happened in certain scenarios and whether a team won or loss beyond that scenario.  By looking at all of those situations, you can develop historical-based probabilities on whether a team wins or not.  By knowing the inning, outs, baserunners and locations, and score differential, you get an average probability of whether a club may win or lose.

By taking that data and looking at how the probability can change, we end up at what is called a Leverage Index.  In general, these conditions are easy to see.  When a club is up seven runs in the ninth, the leverage index would be low because it does not really matter what happens with a single batter.  The differential is too great.  In a tighter game where the difference is a run, you can see how much more important that event is.

I won't go deeply into how it is all calculated, but I will provide a link to Leverage Index in certain scenarios and note the following:
Very High Leverage ... greater than 3.0
High Leverage ... 1.5 to 3.0
Medium Leverage ... 0.8 to 1.5
Low Leverage ... less than 0.8
The Orioles were facing a 1.6 Leverage Index in the bottom of the sixth inning, which would indicate that the club has entered a period where it is important to fight for the win as a single plate appearance could result in a rather poor outcome.  A modern bullpen when called upon would see this as an important moment to put in a rather solid reliever.  It is a role that Buck Showalter has often assigned to Mychal Givens.

On that night, it did not work out.  Givens was taken deep and the Orioles found themselves in a hole.  Buck, having a short bullpen, then tabbed Pedro Araujo in what would be considered a low leverage position (0.6).  Things quickly went south and the Orioles hung on with one run down and the bases loaded, two outs, in the bottom of the seventh.

At this point, there is a decision to be made.  The bullpen has one rested reliever left, Nestor Cortes, Jr.  The Leverage Index at this point is 2.4, which means the outcome of this event will likely have considerable impact on the game moving forward.  Do you go with the rested arm or do you send Darren O'Day out there for the second night in a row?  More so, do you have the foresight of this predicament to get O'Day up in the bullpen when Araujo immediately looks bad as he pitches to his first batter?  Do you get O'Day up while knowing that maybe Araujo gets lucky and settles down?  Do you try to sneak into the eighth or ninth inning where maybe the Leverage Index is higher for you to utilize O'Day?

It is a tough question to answer.  Yes, putting Givens in seems pretty easy and straightforward.  Putting in Araujo also seems like a no-brainer.  From there it got messy.

But let us go back to general bullpen usage.  Below I took a few excerpts out of the Leverage Index values link to earlier in the article.  What we see are generally preferrable times to bring in a very good reliever (italics) and your best reliever (bold) based on being the visitor and starting off the bottom of the inning.
Bases Empty No Outs
Bottom of Up 2 Up 1 Tie Down 1 Down 2
1st 0.9 0.9 0.9 0.8 0.6
2nd 1 1 0.9 0.8 0.6
3rd 1 1.1 1 0.8 0.6
4th 1.1 1.2 1.1 0.9 0.6
5th 1.3 1.3 1.2 0.9 0.6
6th 1.4 1.6 1.3 0.9 0.6
7th 1.6 1.9 1.5 0.8 0.4
8th 1.8 2.5 1.8 0.6 0.3
9th 2 3.6 2.3
With this initial setup, you can see how being up a run can make situations more important than they might seem and suggest a different usage.  Strong middle relievers should be considered in the sixth inning, like Givens.  Likewise, closers should be considered for entry into a close game in the ninth, which is something that Buck Showalter will live with on his non-use of Zach Britton in the Orioles only 2016 playoff game.

It is important to remember that these are initial conditions.  As baserunners appear and out accumulate, these numbers can go up or down.  For instance, the bottom of the third with bases loaded and down a run or two is considered a very high leverage scenario (3.1).  Ideally, you would put a closer in that situation, but the way bullpens are constructed it would be difficult to justify killing the bullpen for a game that is still pretty young.  So the number is not all, but it does provide a decent understanding of important scenarios and how maybe it is important to use high end relievers early or use your best pitcher in non-save scenarios.

1 comment:

Boss61 said...

I find this very insightful. Less clear is at any instant, who is the best reliever, vs. second best, etc. Variables such as tiredness of the reliever (and the bullpen overall), the weather, who is at bat, etc. also must factor in.