The Lions made a good move signing Rudi Johnson to a one-year contract, a deal that became official earlier today.

Johnson is a clear upgrade over Tatum Bell as the No. 2 runner in Detroit's backfield, and if his balky hamstring holds up (and there's no reason it shouldn't on a one-year contract) he's a welcome insurance policy for rookie Kevin Smith.

This isn't Adrian Peterson we're talking about, but it's not a broken-down Shaun Alexander, either. Johnson had three straight 1,300-plus yard seasons from 2004-06, and at 28 (29 in October) still has a couple productive years left. Remember, he hardly played his first two seasons in the league behind Corey Dillon, and last year he logged about half a season's work (170 carries) splitting time with Kenny Watson.

I'm in the camp that doesn't believe Johnson will challenge Smith for the starting job. Smith had a good camp, has excellent vision and cutting ability, and his so-so preseason stats were more a product of the offensive line than anything he didn't do. But rookie running backs have a tendency to wear down over the course of a 16-game season, and the more Johnson can spell Smith the better.

I wouldn't expect Johnson to be long in Detroit, either. He's no longer a 350-carry back — if he was, the Bengals wouldn't have cut him — but he'll want a chance to start next year and with the dearth of quality runners should get it somewhere. Still, coaches weren't comfortable heading into the season with Bell an injury away from the feature role. They made a low-cost, low-risk move that should yield minor dividends.