Why Fans Should Be Excited About the 2014 Orioles Bullpen

Last week, Matt Kremnitzer wrote an article about the Orioles bullpen in which he compared the 2012 bullpen to the 2014 bullpen. In this article he included a chart comparing certain statistics of the 2012 and 2014 bullpen and noted the results have been reasonably similar even if the 2012 bullpen has been better. 

I was thinking about this article and how it measured bullpen performance. Bullpen performance is typically measured by taking the results for each reliever and weighting them by the number of innings pitched by that reliever. Two relievers that each threw sixty innings would have the same amount of weight when determining reliever performance. A reliever that throws sixty innings would have twice the weight as one that threw thirty innings.

The problem with this method is that it presumes that all relievers in the bullpen should be treated equally. I'm not sure I would do that because it’s only logical that the performance of a closer is more important than the performance of a long man. The closer usually comes into games in the ninth inning when the game is close while the long man comes into the game considerably earlier when the game isn’t close. If the long man gives up a run then little harm is done but if the closer allows a run then it could lead to a blown save and a loss. Teams would rather have a closer with a 0 ERA than a long man with a 0 ERA and it only makes sense to reflect that in bullpen performance. All relievers aren’t equal and it’s necessary to find some method of ensuring that the most important relievers have the most value in these calculations.

Tom Tango developed a statistic called leverage index (LI). This statistic measures how important a particular situation is in a baseball game depending on the inning, score, outs, and number of players on base. It is possible to use this statistic to determine which relievers have been used in the most important situations and therefore which relievers are most valuable. This allows us to quantify the difference between a closer and a long man. The leverage index most commonly used is one that measures a player’s average LI for all game events known as pLI. In fact, Fangraphs uses this leverage index when determining pitching WAR. Another leverage index is called gmLI. This index measures a pitchers average LI when he enters the game. I personally believe that gmLI is a better metric than pLI and will therefore use gmLI in this article. 

Fangraphs provides the gmLI for each reliever. It is possible to use this statistic to weight bullpen performance by the importance of each pitcher as well as by innings thrown which should result in a more accurate measure of bullpen performance than considering each pitcher to be of equal performance regardless of role. We can use this statistic to see how the Orioles 2014 bullpen compares to other teams bullpens. In addition, I’m only using relievers on an active roster because Orioles’ fans are excited about their current relievers. Orioles’ and other teams’ fans couldn’t care less about guys like Evan Meek.  

This table shows the number of pitchers used by each bullpen, the bullpen’s ERA without using leverage, the bullpen’s ERA using leverage and the difference between the two.

Team	Pitchers	Non-Leveraged ERA	Leverage ERA	Difference
Rays	10	3.12	3.14	-0.02
Mets	11	3.01	3.02	-0.01
Mariners	11	2.49	2.49	0.00
Tigers	18	4.28	4.24	0.04
Marlins	14	3.07	3.02	0.05
Giants	10	2.65	2.60	0.05
Twins	11	3.33	3.25	0.07
Blue Jays	16	3.75	3.66	0.09
Orioles	12	3.07	2.99	0.09
Rockies	15	4.84	4.74	0.10
Athletics	12	2.72	2.62	0.10
Indians	14	2.84	2.72	0.12
Astros	16	4.85	4.73	0.12
Nationals	12	2.81	2.69	0.13
Yankees	16	3.33	3.19	0.13
Braves	14	3.19	3.06	0.14
White Sox	16	4.28	4.14	0.14
Diamondbacks	15	3.75	3.60	0.15
Padres	12	2.39	2.22	0.18
Rangers	23	3.96	3.76	0.20
Cardinals	14	3.68	3.48	0.20
Cubs	15	3.45	3.24	0.21
Brewers	15	3.56	3.31	0.24
Angels	20	2.96	2.70	0.26
Pirates	14	3.40	3.10	0.29
Reds	12	3.96	3.58	0.38
Red Sox	14	3.27	2.82	0.45
Dodgers	13	3.75	3.27	0.48
Phillies	14	3.67	3.19	0.48
Royals	15	3.18	2.38	0.79

Using this method shows the strength of the Royals bullpen. The Royals have only three relievers that have pitched over ten innings with a gmLI over 1.1. All three of those relievers have an ERA under 2. The backend of the Royals bullpen has been dominant and as a result their bullpen ERA using leverage is considerably lower than their bullpen ERA not considering leverage. Likewise, the Phillies have had Papelbon and Adams pitch most of their high leverage innings and both of them have low ERAs. This method makes them look better than they would otherwise.

This does little to explain why people should excited about the Orioles bullpen. While our leveraged ERA is 2.99 this is only good for tenth in the majors. The difference between our leveraged bullpen ERA and non-leveraged bullpen ERA is miniscule and one of the lowest in the majors. In addition, the 2012 bullpen is still better then the 2014 bullpen even when considering leverage.

Fortunately, this next table may answer this question. This table consists of the team name and the average leverage of the bullpen and shows that the Orioles bullpen has the second highest game leverage.

Team	Average Leverage
Rangers	0.997
Blue Jays	1.010
Dodgers	1.019
Padres	1.023
Giants	1.050
Nationals	1.071
Twins	1.077
Astros	1.087
Royals	1.090
Athletics	1.106
Brewers	1.115
Tigers	1.117
Indians	1.120
Rockies	1.121
Cubs	1.156
Mets	1.165
Diamondbacks	1.181
Pirates	1.184
Mariners	1.191
Phillies	1.193
Angels	1.194
Reds	1.224
Marlins	1.229
Rays	1.231
Cardinals	1.252
White Sox	1.270
Red Sox	1.286
Braves	1.312
Orioles	1.340
Yankees	1.387

Orioles fans are excited about their bullpen because it has done well in high pressure situations. As I write this post, O'Day has just struck out Abreu and Garcia with runners at first and second to maintain a one run lead while Britton had a one-two-three ninth to pick up his 27th save despite having little margin for error with just a one run lead. The Orioles have needed their bullpen to come through in the clutch this season and it has met the challenge. As a result, the Orioles are in excellent position to clinch the division and fans are showing their bullpen the love.