Last night, I was looking at a graphical representation of Mike Rivera's game log. (Can't link it, sorry, but you can look at the BR version, here.) It's just bizarre that he spent the entire season with the team--healthy, as far as I know--and started less than 10% of the team's games.
All this thanks to Jason Kendall's durability and...game-calling ability, apparently. It certainly isn't because of anything Kendall brought to the lineup, except for maybe contact skills. (Contact in the form of groundouts, of course.)
Anyway, here's what Kendall's trends have looked like over the last four years. (Again, if you're new to this stuff, read the intro to the JJ Hardy article.)
That's just not pretty. What surprises me a bit is that, aside from a slight uptick in mid-07, Kendall has been sliding downward for almost three years straight. His April was kind of exciting for us, but MINER sees right through all those groundball hits.
For reference, the NL average catcher has a line of 255/328/387, for an OPS of 715, 65 points higher than Kendall's 08 season. (Once you adjust these neutral projections for the NL, the projection is also in the 640-650 range.)
There's only so much room for improvement at catcher--short of trading for or developing a real weapon like Mauer, Martin, or Soto, you're left with guys like Kendall and Torrealba on the free-agent market every year. But for the sake of illustration, the simple runs created formula suggests that Cubs catchers generated 102 offensive runs, while Brewers catchers were worth 65. That's almost four wins, just at one position.
Maybe Kendall's experience and the pitchers' comfort level with him is worth three or four wins. But I doubt it.