One of the most difficult things to quantify in baseball -- a sport that attempts to quantify everything with some sort of stat -- is the value provided by a catcher in terms of how well he works with pitchers. The reality is we mostly have to go off of pitcher performance among common catchers and just listen to the pitchers, managers and coaching staffs.

One man who has been receiving praise on this front for years and is now in his final season is David Ross of the Cubs. His pitchers love him. On that front, ESPN researcher Mark Simon tweeted the following on Monday:

How does that measure up to the rest of the catchers this season? Unbelievably. Let's expand upon that. Including only catchers with at least 200 innings behind the plate this season, here are the top 10, ranked, in catcher ERA (to be clear, this is the ERA of the pitchers when each particular player below is the catcher).

Catcher Team Innings caught Catcher ERA
David Ross
Cubs 245.1 2.09
A.J. Ellis
Dodgers 241.2 2.42
Miguel Montero
Cubs 250 2.99
Buster Posey
Giants 413.1 3.24
Wilson Ramos
Nationals 414.1 3.37
Kevin Plawecki
Mets 305.2 3.39
Chris Iannetta
Mariners 423 3.51
Bobby Wilson
Rangers 239 3.54
Dioner Navarro
White Sox
311 3.56
Alex Avila
White Sox
234.2 3.68

Ross' pitchers really love throwing to him. USATSI

Ellis has gotten to catch Clayton Kershaw 10 times, so it really is remarkable how high Ross sits, despite having only caught Jake Arrieta three times. Of course, the entire Cubs' pitching staff has been awesome this season, but can't we give some of that credit to Ross and Montero? Remember, the Cubs decided to use this duo instead of Welington Castillo -- a far superior offensive player who has a 4.99 catcher ERA this season.

For those curious about a pair of Missouri catchers with great reputations, Salvador Perez sits at 3.99 and Yadier Molina at 4.02.

Obviously this isn't the be-all, end-all behind the plate and the quality of pitching staffs makes a big difference, but it can be a piece of the puzzle. If you disagree, just ignore it. That's cool, too.