The first statistic that we will take a look at is time in the pocket, a very important variable when dealing with quarterbacks. In average time in the pocket, which includes time before a sack, a pass attempt and a QB scramble, Kevin Kolb has a slight advantage over John Skelton at 2.84 seconds to 2.63 seconds. In average time to attempt Kolb once again has the advantage, average 2.59 seconds to Skelton's 2.50. Lastly, we'll take a look at average time before a sack, in which Skelton holds a distinct advantage over Kolb at 3.31 seconds before a sack, to Kolb's 2.28 (which also happens to be the fastest average time to get sacked in the NFL).
Time in the pocket alone does not tell the whole story though. Next up we will look at the pressure given up to each quarterback. Kevin Kolb was pressured on 42.4% of his total dropbacks, and sacked on 29.3% of those same dropbacks, at a ratio of 1.45 pressures/sack. For Skelton, he was pressured on 36.4% of his dropbacks and sacked on 19.7%, for a ratio of 1.85 pressures/sack. In spite of this, Kevin Kolb has a much better completion percentage, 54.2%, than Skelton, 43.6%, while under pressure.
What can we decipher from this? Simply put, Kolb was sacked at a much higher rate than Skelton, duh. One may posit that Kolb was only sacked more because of his tendency to scramble and put himself in a position to get sacked, but per PFF Kolb is only credited with be at fault for 3 of his sacks (Skelton is credited for 2). The fact is, Skelton and Kolb played very similarily when put under pressure, ergo one could assume that teams wouldn't blitz one QB significantly more than the other. In fact, when Skelton did have longer than 2.6 seconds to attempt a pass, his numbers fall drastically, a 46.8 completion percentage and a 45.8 quarterback rating, while Kolb holds a 56.8 completion percentage and an 89.4 QB rating.
So then, what changed with the offensive line? First one could point to the insertion of Nate Potter as the teams left tackle over the D'Anthony "The Human Turnstile" Batiste. Potter has only given up two sacks over the previous three games. Another factor to take into account would be the improved play of rookie Bobby Massie. Over that same three game span Massie has yet to allow a sack, and the offensive line as a unit has only allowed a total of 5 sacks, while also cutting down the QB hurries significantly as well.
Early in the season, the tackle combination of D'Anthony Batiste and Bobby Massie were given up pressures and sacks at a historic pace, easily the two worst tackles statistically in the NFL, and due to this Kevin Kolb was getting sacked at a tremendous rate, but still playing pretty good football, and more importantly protecting the football. Recently, Potter and Massie have at least played at an adequate level, cutting down their pressures given up significantly. Granted, Skelton does have good pocket presence which definitely helps in limiting the sacks, but his lack of mobility also hurts. Just like Kolb's arguably lower pocket presence can hurt, but his mobility allows him to avoid some sacks as well.
Simply put the biggest reason for the improvement of the offensive line is not because of either QB, it is because of the play of the Arizona Cardinal's rookie tackles. Their play, coupled with the return of OT Levi Brown next season poses an interesting dilemma, do the Arizona Cardinals still view OT as the be all to end all priority of the offseason? Either way, it would appear as though Kolb (with a restructured contract) should return next season, and with an improved offensive line can be at least an above average quarterback, if not better.