Loss leader

 It's not quite true that running backs are a dime a dozen these days in the NASH-unal FOOT-ball League. Why, you can probably get 12 cents for a dozen in today's market. Maybe even 13 if you sell it hard enough.

Oh, they probably still have some value, even in an NFL that's 95 percent pitch-and-catch. But they wear out fast and, like new cars, they begin to depreciate the minute you drive 'em off the lot in the second or third round of the draft.

Know how I know this?

Because Dalvin Cook knows this.

He's only 27 years old and he's lugged it for 5,993 yards in six seasons, which already makes him the Minnesota Vikings' third leading rusher all-time. Last season he was sixth in the NFL in rushing, with 1,173 yards. He also caught 39 passes for another 295 yards.

All that, and the Vikings dumped him anyway.

They dumped him because re-signing him would have meant a $14 million salary cap hit, and not even a 27-year-old running back who's still among the best in the league was deemed worth that. Better to save those pennies for, I don't know, an extra wideout or a backup tight end.

None of us who remember watching Barry Sanders or Walter Payton or Earl Campbell can even conceive such a thing. Those worthies, and their contemporaries, were just getting started at 27. Now the Vikings clearly think 27 is a sell-by date.

This means they're either stupidly tossing him aside well before he's used up, or they're prescient enough to see signs of his inevitable decline. Because that's what happens to running backs in today's NFL.

When they fall off, see, it tends to happen suddenly. So maybe the Vikes looked at, say, the fact Cook's yards-per-carry has declined every one of the last three years, and saw in that the edge of the cliff approaching.

Time will tell. For now, Dalvin Cook is exhibit A that NFL teams consider running backs a loss leader. To be sure, lots of folks will line up to sign him -- the Dolphins have been most prominently mentioned as Cook's landing zone -- but a long-term deal is probably not in his future.

Unless, that is, some other team turns out to be dumber than the Vikings.

Yeah, I know. But it could happen.