Kolb to Skelton: What's the difference?

Much has changed since Arizona Cardinals coach Ken Whisenhunt named John Skelton over Kevin Kolb as his starting quarterback entering the 2012 regular season.

An ankle injury sidelined Skelton in the opener. Kolb led the team to a comeback victory. The team won its first four games, then lost its past two.

Now, with Kolb sidelined indefinitely by what we might loosely call injured ribs, Skelton is back in the lineup for the first time since the opener.

What difference will Skelton make? Whisenhunt has long said the the team feels it can win with either quarterback. The team has done just that, winning 11 of its past 15 games dating to last season.

The chart shows stats for both quarterbacks since Week 12 last season. I chose that starting point because both players have had a similar number of snaps during that period. Both players have benefited from stronger defensive play during that period.

Injuries to key offensive players have affected Kolb to a greater degree, especially recently. We should keep that in mind when looking at the numbers.

Kolb has been more efficient as a passer. He has done a better job limiting interceptions. Kolb has also taken far more sacks. Injuries on the offensive line have played into that disparity.

ESPN Stats & Information provided figures for the chart. Success rate shows what percentage of quarterback action plays -- passes, runs, penalties, etc. -- have improved the team's win probability. The Total QBR scores for both players lag below the 50-point average on a 100-point scale.

Larry Fitzgerald has a similar number of targets and receptions with each quarterback over the period in questions. He has far more yards after the catch with Skelton (8.2 per reception to 3.5) and far more plays covering 30-plus yards (seven to one).

Andre Roberts has the same number of receptions with each quarterback (24), but far more yards after the catch (5.5 to 2.2 on average) with Kolb.

Early Doucet has the same number of targets (27) and receptions (13) with each quarterback during this time. He has far more yards with Skelton (215) than with Kolb (82). That includes 7.7 yards after the catch with Skelton and only 1.7 with Kolb.

Many factors could explain some of these disparities. I don't know for sure what they are.