Diamondbacks Free-agent Discussion, #8: Jeff Mathis

The D-backs signed Jeff Mathis in late 2016, and were under no apparent illusions they were getting an offensive-minded catcher. Even to that point, he had an OPS+ of just 53, and had a career batting average below the Uecker Line, at .197. But what he did bring was an excellent defensive reputation, especially in the area of pitch-framing - the art of taking a borderline delivery and making it look good enough for the umpire to call it a strike. Steve Gilbert wrote, “The pitchers love throwing to him, believing that he calls a good game and is able to bring out their best. In the organization’s mind, whatever they get from Mathis on the offensive side of things is a bonus. They are more concerned with his defense.”

That’s fortunate, because there really wasn’t very much in the way of bonus from Jeff over the past two seasons. He had fewer home-runs in his time with Arizona than J.D. Martinez did on one night in Los Angeles. While Mathis did manage to surpass the Uecker Line, batting .207 with Arizona, his OPS was only .571, giving him an OPS+ of just 48. Among the 398 players with over 300 plate-appearances in this time, this OPS+ ranks Mathis... 398th. He appeared in only 129 games over the 2017-18 campaigns combined: part of this was by design, as his high since 2011 was 73 appearances. However, he did miss the last six weeks of the 2017 season, after breaking his non-catching hand when it was hit by a foul ball.

With that in mind, it’s perhaps worth looking at how the catching starts broke down over each of the last two seasons.

1. Jeff Mathis - 56/61
2. Chris Iannetta - 70/NA
3. Alex Avila - NA/57
4. John Ryan Murphy - 1/44
5. Chris Herrmann - 35/NA

Avila and Murphy are both under contract for next year, though their offensive output was hardly any improvement on Mathis, each finishing the year with an OPS+ of 59. Whether or not they should look at signing Mathis depends on if the D-backs want to go the three catcher route again in 2019. The main argument in favor, is that it allowed them to pinch-hit for a catcher in the later innings, and still have coverage in the event of injury. Of course that coverage was never needed. The only game in which Arizona used three catchers this year was against the Braves on Sep 6, and by that point the rosters had expanded anyway. Before September, Arizona used even two catchers only about twenty times. ‘

But there’s plenty of evidence Mathis was as good as said in regard to defense, especially pitch-framing. By StatCorner’s catching report, he was in the top ten for all catchers both years by RAA (framing runs above average), and was #1 last season, sitting at 14.1 runs above average. If you accept that figure (and I admit there is some doubt as to the value of framing), that’s about an extra win and a half for Mathis. Considering he started barely one-third of Arizona’s games this year, that would be no small advantage. More broadly, Baseball Prospectu’s FRAA_Adj, which also includes blocking, SBs, etc. rated Mathis #2 this year, at +14.1, a key reason why our catcher defense was the best in the majors by that metric.

There’s also another data point in catcher’s ERA. The pitchers throwing to Mathis had a significantly lower ERA (3.20) than Avila (3.97) or Murphy (4.09). This needs to be viewed cautiously, as there are other factors involved - most obviously, the quality of pitcher. But if you look, say, just Patrick Corbin, the pattern persisted - though small sample size becomes more of an issue. Corbin’s ERA with Mathis was 1.83, a full run and a half lower than to Avila (3.34), who was in turn more than a run an a half better than Murphy (4.95). Gilbert’s statement that pitchers love throwing to Mathis seems to have some basis in the results they obtain when doing so.

So, we have a player who, let’s be honest, is one of the very worst hitters in the major leagues, someone who will also turn 36 not long after Opening Day next season. But at the same time, there’s evidence that he makes the team better, not only his own defense, but also by making the pitchers “better”, through Mathis’s expansion of the strike zone. Whether you think Mathis should be retained is perhaps a litmus test for where you stand on the “defense vs. offense” argument.