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Arizona Diamondbacks 2017-18 off-season issues #4: Catching

The two-headed beast was solid for the D-backs this year, but one head may not be back in 2018.

Los Angeles Dodgers v Arizona Diamondbacks Photo by Christian Petersen/Getty Images

With a score of 6.12, we’re definitely getting into an area of concern now, with a lot more sixes and up. 49.6% of votes were in the 6-8 range here. Though interestingly, at 7.7%, the number of 10’s was slightly less than the 8.6% who expressed the highest level of concern about the Diamondbacks’ starting pitching for 2018.

2017 starters

  • Chris Iannetta: 70
  • Jeff Mathis: 56
  • Chris Herrmann: 35
  • John Ryan Murphy: 1


  • 1.2 bWAR below average at the position (23rd in MLB)
  • .234/.318/.445 = .763 OPS, 27 HR, 71 RBI

Depth chart

  1. Jeff Mathis
  2. Chris Herrmann
  3. John Ryan Murphy
  4. Oscar Hernandez

The low overall production and subsequent ranking above is a little unfair, because bWAR does not do a good job of taking into account defensive elements like blocking. In that area, the Diamondbacks did substantially better, especially in the field of pitch framing. I’ll look at that in more detail in a separate piece, but Baseball Prospectus has the stats for catchers: this has the D-backs 9th overall in the majors and 4th in the NL for catcher defense. This is mostly the result of framing, evaluated as having saved 12.5 runs, sixth most in MLB. A weakness was blocking, where Arizona was 23rd, at -2.0; with a league-high 82 wild pitches, that shouldn’t be much of a surprise.

The offense was driven by Iannetta, whose 114 OPS+ was twice the other regulars, Herrmann coming in at 55 and Mathis at 51. The latter’s lack of offense was expected: he was always regarded as defense-first, and delivered on that. Of the 411 players with 750+ PA over the last five seasons, Mathis ranks 411th by OPS+, and it’s not close. He’s at 51, so this season’s production was right in line with that. The next lowest is 62 - Nick Ahmed, actually. [Fun fact: of all players with a career sub-Uecker Line BA, only the worst hitter in baseball history, Bill Bergen, has more PA than Mathis. Like Mathis, Bergen was a great defensive catcher, who once threw out six runners in a game]

When we went into the season, it wasn’t clear what the balance would be between Iannetta and Mathis. The final ratio - about four for Iannetta, three for Mathis and two for Herrmann - is likely not too far off what we would have wanted. But this was colored by Mathis being one of our apparently endless stream of players whose hands were broken this year. He started only one of the last 37 games,. so to see what was intended we should look at the first 125 and pro-rate that for the season. This shows Herrmann as the main beneficiary of Mathis’s down-time.

  • Chris Iannetta: 70
  • Jeff Mathis: 66
  • Chris Herrmann: 26

It may be no stretch to call Iannetta the most important free-agent for the D-backs to re-sign this winter. His more hitting-oriented approach was a great mesh with the defensively-minded Mathis, and I think both men were a significant factor in the vast improvement previously noted in the team’s starting pitching this year. Disrupting the relationships forged this year is something I’d consider perilous, though I would like to see a bit more flexibility in the “personal catcher” situation. Better to have at least some familiarity with other battery-mates, rather than be suddenly required to get it, when your guy goes down.

On the other hand, Herrmann became a popular whipping boy on social media, virtually every time he was in the line-up. The metrics generally concur. His -0.6 fWAR and -0.8 bWAR were the lowest on the team, and that’s without taking into account his below-average catching defense, where he ranked 101st of 110 catchers by Fielding Runs Above Average., at -7.7 runs. The team may look at Murphy, who has stellar defensive numbers in the minors, as a replacement for Herrmann this year, with the longer-term aim of taking over from Mathis, who’ll be a free-agent at the end of next season. But getting Iannetta, or a credible alternative, should be a top priority this winter.