Catcher ERA

Justin Verlander had another rocky start yesterday, surrendering 7 ER in 6 innings.  In his last 15 starts, Verlander has a 5.22 ERA in 91 1/3 innings with a 1.57 WHIP and 82 strikeouts.  There have been several theories in why Verlander is having a down year this year, with the most likely case is that his mechanics are off, causing command issues.  

Another theory going around is that Verlander is much more comfortable with Alex Avila catching than Brayan Pena (based on something Verlander supposedly said on 97.1 this morning).  After all, it was Pena that was catching Verlander last night.  There has been several articles written about the flaws of using catcher ERA because of external factors outside of the control of the catcher, mainly including the talent of the pitcher, the ballpark and the defense.  I crunched some numbers to put this study to the test using Tiger starting pitchers.  I'm also including Fielding Independent Pitching (FIP) since the differences in ERA can be more luck-based than skill-based.  

	Alex Avila			Brayan Pena
	IP	ERA	FIP	IP	ERA	FIP
Justin Verlander	67 1/3	3.74	3.54	65 1/3	3.99	3.26
Anibal Sanchez	77 2/3	2.67	2.75	26 1/3	2.73	1.34
Max Scherzer	81 2/3	3.09	2.29	56	3.21	3.57
Doug Fister	78	4.15	3.64	49	3.49	3.03
Rick Porcello	79	3.30	3.31	11	5.73	3.87
Total	383 2/3	3.38	3.09	207 2/3	3.60	3.08

The Tigers starting pitchers do have a lower ERA using Avila (3.38) over Pena (3.60).  However, the differences in FIP is insignificant (3.09 for Avila and 3.08 for Pena).  It looks likes pitching performance is not dependent on the catcher and that any big differences shown in this table can be explained away by small sample sizes.  Verlander has close to about the same number of innings using Avila and Pena and his ERA and FIP differences appear to be insignificant.  

This isn't to say that a pitcher isn't more comfortable using a certain catcher.  Many pitchers have used a "personal catcher" throughout the years.  It's this psychological part of the game that often gets lost in advanced stats.  Similar to how relief pitchers like to have certain roles in the bullpen or certain batters like to hit in certain spots in the lineup.  The numbers do not show a significant difference, but the mentality is there nonetheless.  It is possible that Verlander is more comfortable using Avila and this mindset might be the first step in breaking Verlander out of this slump.