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Diamondbacks Game Preview #136: 9/7 @ Padres

Fiddling around with another measure of bullpen suckiness

San Francisco Giants v Arizona Diamondbacks Photo by Kelsey Grant/Getty Images

Today's Lineups

Josh Rojas - 3B Ha-Seong Kim - SS
Ketel Marte - 2B Juan Soto - RF
Jake McCarthy - RF Manny Machado - 3B
Emmanuel Rivera - 1B Josh Bell - DH
Daulton Varsho - DH Jurickson Profar - LF
Corbin Carroll - LF Wil Myers - 1B
Cooper Hummel - C Jake Cronenworth - 2B
Alek Thomas - CF Austin Nola - C
Geraldo Perdomo - SS Jose Azocar - CF
Tommy Henry - LHP Yu Darvish - RHP

As if anyone needed it, last night was further proof that the D-backs’ bullpen is an issue. Between them, our two main closers, Ian Kennedy and Mark Melancon, have combined for 27 saves... and 17 losses, in only 95 innings of work. With another Win Probability well into the negative eighties, these two men have now combined to be worth -312% there this year. Oh, yeah: they’re also far and away the most expensive relievers on the roster, earning close to $11 million between them. I think Caleb Smith is about the only other bullpen arm who is not at league minimum this season.

But I was tooling around with some figures, and decided to try and come up with a measure of relief effectiveness based on Win Probability and innings pitched. Keeping it simple, I went for WP divided by IP. Basically, it’s the change in the chances of a team winning for every inning pitched by the reliever. I drew an arbitrary, but it feels reasonable, cutoff of thirty innings of work this season, which gave me 226 qualifying relievers. That’s an average of about 712 per team, so more or less a full bullpen. The resulting metric had a range of 7.15 down to -4.64: Coincidentally, the median guy is Caleb Smith, at 0.49. it makes sense it skews positive, as most really bad relievers probably will get DFA’d before reaching 30 innings.

Here’s a link to the full spreadsheet. By this metric, the best reliever in the majors this season is... Daniel Bard, the Rockies closer and former D-backs motivational speaker. While other relievers have a lower ERA, he has piled up +358% in barely fifty innings for a score of 7.15. The worst, to my surprise, is not Melancon, but Art Warren of the Reds: In 36 innings, he is at -167% of WP, for that -4.64 score. Melancon does rank 225th of 226, at -4.31, and Kennedy is not much better, his -2.62 coming in 210th. But what stands out for Arizona in general is they do not have a single reliever in the top 60. Our highest ranked arm is Kyle Nelson, #61 with a score of 1.60. Here’s the full list of Arizona bullpen pitchers:

  • #61: Kyle Nelson, 1.60
  • #96: Joe Mantiply, 0.83
  • #113: Caleb Smith, 0.49
  • #162: Noe Ramirez, -0.80
  • #210: Ian Kennedy, -2.62
  • #225: Mark Melancon, -4.64

Collectively, Arizona’s bullpen has posted a collective WP of -414%, with ranks them 28th in the majors, ahead of just the Giants (-419%) and Marlins (-480%). So they’re basically one more meltdown and blown lead away from being the worst in the majors...