Pitch framing is still a tough thing to qualify but if you want any amount of baseball at all you know when a catcher receivers the ball well and when he doesn't. The Pirates have had some brutal receiving catches over the years which include Ryan Doumit and Rod Barajas and while Michael McKenry is a solid bench option he does not receive the ball very well. According to Mike Fast over at Baseball Prospectus who charted runs saved via pitch framing from 2007-11 Martin ranked second only to Jose Molina in total runs saved, and it was by a mile from the next closest competitor. Like I said pitch framing is really hard to qualify and while Mike tackled it pretty well it would be foolish to look at only offensive numbers when talking about Martin and why he was brought to the Pirates.
Today FanGraph's Jeff Sullivan took a much more in depth look at what Martin really brings to the Pirates. If you haven't read this yet then you need to go and do so. It is a really awesome article and while it doesn't excuse his poor offensive play it highlights something that is often overlooked by people.
Just to take a quick piece of what he is talking about here is a taste when he looks at Diff/1000 which is a stat that refers to the difference between actual strikes and expected strikes per 1,000 called pitches:
The team with the biggest gain so far is the Brewers, at +39, and I imagine that has a little something to do with Lucroy being healthy. Lucroy is outstanding, and last year he had to miss a lot of time. The team with the second-biggest gain so far is the Pirates, at +35. No one else has jumped more than +19. The big difference with the Pirates is that now they have Russell Martin behind the plate a lot of the time.
For the rest please go and read the article. While you can't defend how bad his offense has been so far two things are true about Martin that mildly get overlooked: his on base ability (his OBP is 102 points higher than his average) and his defensive ability (READ THE ARTICLE).
You are welcome people.