Adrian Peterson will celebrate his 29th birthday on Friday. Wait. Strike that. He's a running back. They don't celebrate birthdays.

Yes, Peterson could be the exception to the rule. Again. He could blow by 30 like a locomotive, break Emmitt Smith's rushing record and play until he's 36, 37, who knows?

But it is interesting or, better yet, a sign of the times that Peterson's dependable, primary backup the past four years won't be around as Peterson heads into the stage of his career when common sense suggests he will need a dependable, primary backup most. It's also a sign of the times that Peterson's longtime dependable backup, Toby Gerhart, left without a peep to sign a three-year, $10.5 million deal with the Jaguars.

The Vikings aren't doing anything unusual by not rushing to sign a veteran running back to replace Gerhart. Not in a league where the value placed on most veteran running backs lies somewhere south of the value placed on kickers.

There are so many good, young running backs available that it makes little sense to make a big investment in a veteran with NFL wear and tear.

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