Preview, #14: 4/12 vs. Padres

The Arizona bullpen currently sits 14th in the National League, with an ERA of 6.80. Now, admittedly, that is slightly skewed by John Ryan Murphy, whose single appearance is responsible for more than a run of this figure - without him, our reliever’s ERA drops to 5.65. But there have still been some early bumps from people who were expected to be better. In particular, Andrew Chafin and Yoshihisa Hirano have each an ERA of 6.23, combining for seven walks in just 8.2 innings of work. The long-ball has been a particular issues: again, discounting Murphy, 10 in 43 innings. Matt Koch has allowed six over just nine IP. No pitcher in the entire major-leagues, starter or reliever, has given up more going into play today.

Yet this hasn’t “cost” the team too much. Despite that ERA, the Arizona bullpen has a collective Win Probability which is fifth-best in the league (albeit only fractionally positive at +1% through the first 13 games). They have fractionally more shutdown appearances (10) than meltdown ones (9). Both of these figures suggests that a lot of those runs allowed were in garbage time, with the game already well out of reach. Chafin actually leads the bullpen in Win Probability so far, at +39%, though the vast majority of that (+33%) came in one appearance, resulting mostly from his bases-loaded, no outs Houdini-like act of escape on Wednesday night.

At the extreme other end is the man with the same ERA as Chafin - Hirano has been worth -102% of WP to date. Yoshi has yet to have a shutdown appearance, but has posted three meltdowns in only six outings. That’s in sharp contrast to his 2018 numbers, when his ratio in this metric was a stellar 37:10, and he had three meltdowns over the entire first half of the season (#4 didn’t show up until July 21st). Of course, small sample size warnings apply: from July 11-30 last year, Hirano had an 8.10 ERA over 6.2 innings. So it could be that this is just a similar rough patch, amplified by occurring at the beginning of the season. But the sooner, good Yoshi returns to our bullpen, the happier I think we’ll all be.