Charting Mariners Reliever Usage

Given the turmoil and general cursedness/curphusness of the Mariners bullpen this year, it’s not too surprising that crisply defined bullpen roles have failed to emerge. Each game it feels like Servais surveys the bullpen, shrugs, and then uses whatever reliever pops up on his Magic 8 ball (OUTLOOK NOT SO GOOD oh time for Peralta!). I’m sure it’s not as random as that, but with relievers getting taxed by a faltering rotation and a seemingly endless hokey-Tacomey (you put your David Rollins in, you take your Cody Martin out, you mix it up with Aro and you shake it all about), the bullpen roles can be a challenge to understand. I thought it might be interesting to take a stab at who gets what slice of the pie by graphing average innings worked against average leverage index (pLI), with the following result:

A few caveats:

• I included Tony Zych, David Rollins, and Steve Johnson, all of whom we will probably see again at some point, as well as Cody Martin, that tiny lonely green dot all off in the corner, because despite the small sample size it’s interesting to see how he was used (long relief, low leverage), but did not include Jonathan Aro just because his data wasn’t up on Fangraphs yet;
• the heavy black line on the horizontal axis represents an average leverage index of 1.0; the heavy black line running vertically is meant to divide a five-out 8th/9th appearance, for example, from something that could be considered longer relief;
• I have never made a chart (don’t even have Excel!) and had to take remedial maths at my liberal arts college and very often count on my fingers, so take this all with a veritable lick of salt.

Looking at the graph, a few things stand out to me:

1. If I were MiMo, I would not be concerned about my job security. Look at his little pink unicorn dot all off by itself. As long as the rotation continues to stumble/suffer the curse of a vengeful mer-goddess, a reliable long reliever is going to be a valuable commodity.
2. Working to the left from the MiMo dot: Edwin Diaz has stepped in admirably for the injured Tony Zych. Both of them have shown to be good for a couple innings of work, but Diaz has done it under much tougher circumstances. It will be interesting to see how this shakes out when/if Zych is able to rejoin the bullpen this year.
3. The lower-left edge of the quadrant can be visualized as one of those speak-and-say toys, but with interchangeable bullpen arms (the curphus says meeeeep). Given the amount Nuño has been used this year, I was surprised to see that his average appearance per game is still about an inning. He and Monty have appeared in the same number of games, but MiMo has pitched over ten more innings. I was surprised when Stevie Johnson was DFA’d, as he’d been mostly effective, but looking at his position on the chart it’s clear what Dipoto meant when he said they needed someone with more “length” in his game.
4. Joaquin Benoit is the company china. He’s the only reliever here who averages less than an inning of work per appearance. Balancing Benoit’s delicate arm requires relievers who can go multiple innings, adding to the value of Diaz/MiMo.
5. Nick Vincent has been, lowkey, one of the best pickups Dipoto made in the offseason. Durable, able to pitch in high leverage spots, able to go multiple innings if necessary, and sporting near-career highs in K% (29.6%) and BB% (5.9%), Vincent is the dark horse of this bullpen.

As guys get healthy/fall apart trying to hold the tatters of the rotation together, this will obviously shift. But it seems clear that, while not relying on any strictly defined bullpen role outside of Cishek’s, Servais nonetheless has certain guys matched to certain situations. Now hopefully they can all get going in the right direction at the same time.