Impact of Peterson's injury on power, speed

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Adrian Peterson continues to rehab from a knee injury he suffered in Week 16 against the Redskins.The Minnesota stadium debate isn’t the only issue Vikings fans are monitoring closely this offseason.

Adrian Peterson is working to come back from a gruesome knee injury suffered late last season. Peterson worked out in front of the media on Wednesday, 137 days after tearing multiple ligaments in his left knee.

Peterson is the face of the Vikings franchise, and one of the most productive tailbacks in league history through his first five seasons.

Most TD 1st 5 Seasons, NFL History

Since his rookie year in 2007, Peterson leads the NFL with 6,752 rushing yards and 64 rushing touchdowns. He has joined LaDainian Tomlinson and Pro Football Hall of Famers Emmitt Smith and Eric Dickerson as the only players to ever amass 6,000 rushing yards and 60 rushing TD in their first five seasons.

Even if Peterson is able to return to the field early in 2012, there’s no guarantee he’ll be able to run with the same strength and speed as in the past.

Running behind a porous offensive line in 2011, Peterson did some of his best work after getting hit, averaging 2.5 yards per rush after contact. Among the 31 running backs who carried the ball at least 150 times last season, only Ben Tate (2.9) averaged more yards per carry after contact than Peterson.

Peterson may not have the same type of wheels as when he ran the 40-yard dash in 4.40 seconds at the 2007 NFL Scouting Combine. Still, he has the speed to break the long run. Over the last three seasons, only Chris Johnson (34) and Michael Turner (21) have more rushes of at least 25 yards than Peterson’s 20.

His knee injury stands as an early-season obstacle, Peterson stands to benefit as much as anyone from Minnesota’s selection of USC offensive tackle Matt Kalil with the fourth overall pick in last month’s draft. While Kalil’s pass protection is considered to be ahead of his run blocking, he’s sure to be an upgrade over the incumbent starter at left tackle, Charlie Johnson.

With Johnson starting all 16 games at left tackle in 2011, Peterson averaged just 3.8 yards per rush on his 30 carries around left tackle. Of the 27 players who rushed around left tackle at least 20 times last season, only three registered fewer yards per carry than Peterson.

In 2010, when Bryant McKinnie anchored the left side of the Vikings line, Peterson averaged 6.6 yards per rush on carries around left tackle, fifth most among NFL tailbacks.