According to Pro Football Focus : 2010 Pass Blocking Efficiency: Guards and Centers  and 2010 Pass Blocking Efficiency: Tackles.

This just goes to show how badly David Diehl and Shaun O'Hara played last year in pass-blocking situations, and how stellar the All-Pro OG, Chris Snee, and the very underrated, Kareem McKenzie, were. The weird thing about this is that we were still ranked 6th in pass protection, as a team, according to Pro Football Focus. I'm not so sure how effective these football "sabermetrics" are, but it's at least worth a look. 

Cowboys' UFA (depending on CBA) Left Tackle, Doug Free, is looking very attractive to me. I wouldn't be surprised if the Giants went after him. Let me not forget to mention that the Cowboys did not franchise him.

In case you're too lazy to click the links:

Kareem McKenzie - 2nd best RT, 6th overall

Chris Snee - 8th best OG

David Diehl - 3rd worst LT, 5th overall

Shaun O'Hara - 3rd worst C

Doug Free (Potential UFA) - 5th best LT, 10th overall