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Montero- The Astros Bullpen Enigma

Monday, Rafael Montero was brought into an 5-3 Astros game to start the bottom of the seventh inning. Two days earlier, Montero was brought a 3-4 Astros game with the bases loaded and one out in the bottom of the fifth inning.

What is leverage and leverage index? Per

Created by Tom Tango, Leverage Index measures the importance of a particular event by quantifying the extent to which win probability could change on said event, with 1.0 representing a neutral situation.

For instance, if a team trailing by three runs had the bases loaded with two outs in the eighth inning, the ensuing plate appearance would register an LI above 1.0. This is because the outcome of the game could dramatically change on that one plate appearance. Conversely, if a team trailing by four runs has a man on first with one out in the top of the ninth inning, the ensuing plate appearance would register an LI below 1.0.

Why it's useful

LI can be used to more easily pinpoint the pivotal moments in a particular game and determine how often players face high-leverage situations.

For the purpose of this article, I am going to evaluate the leverage index when Montero enters the game.

The appearance on 9/16 was the highest game leverage index when he entered the game of the entire 2023 season for Montero. Montero walked the first batter allowing the Royals to extend their lead to 5-3 before recording the final two outs of the inning.

The appearance on 9/18 was the 16th highest of the season for Montero. It did not go well either. The Orioles scored two runs to tie the game.

These two higher leverage situations are a continuation of a trend that the Astros started with Montero in early September. He has been incrementally being used with more leverage after the Stanek injury.

I divided the Montero season into four stretches.

Montero LI stretches

Stretch 1- until 5/15- ROUGH START- Montero is used in high leverage (0.96 average LI) and does not do well by ERA (FIP is not as bad.)

Stretch 2- May 17 to June 25- Bad to Worse- Montero's role is reduced (0.56 average LI) and he pitches worse.

Stretch 3- June 29 to Sept 2- Good Montero?- After stretch 2 and for most of the summer Montero remains in a low leverage role (0.55 average LI) and starts to look like 2022 Montero

Stretch 4- Sept 4 to Sept 18- Stanek gets hurt and leverage increases- Montero's role increases (0.86 average LI)- How will he do now? The early signs are not great but not terrible. As we started, the appearances on 9/16 and 9/18 were not good.

If we divide all of the Montero appearances by leverage index a worrisome trend appears.


When in low leverage Montero has been OK- a little better than average.

When in high leverage, Montero has been bad - 5.59 ERA.

When in medium leverage, Montero has been horrible- 7.80 ERA.

The challenge for the Astros is they NEED Montero to be at least a medium leverage pitcher they can use in the middle innings. They can't.

Where do the Astros go from here with Montero? They hope when Stanek returns that Montero can perform in the low and mid leverage spots and let Stanek take the more mid leverage situations.

Montero has been an enigma - someone hard to understand or explain- most of the season for the Astros. How they manage Montero going forward may play a role in the Astros postseason success.

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