"Happy birthday, Marion Barber. Not that you wanted to be reminded.

Barber turned 27 on Thursday. For an NFL running back, that's almost ancient. Of the league's top 20 for rushing yards last season, only four played at 27 or older.

Or just look homeward to be reminded of the short lifespan of running backs. His father, Marion, gained only 8 yards after turning 27. The father was more of a blocking back during a seven-year career with the New York Jets.

For a back coming off two consecutive inconsistent and injury-riddled seasons, a 27th birthday raises a question for the Cowboys.

How much does Marion Barber have left?

Barber, as is his custom, refused to comment, leaving it to others to face the issue. The Cowboys point to his off-season work, which resulted in a weight loss of about 10 pounds, and frisky attitude during organized team activities as signs Baber is not finished.

"Too old?" an incredulous running backs coach Skip Peete said. "Not at all. I'm looking forward to seeing what he does in camp. He's lean and quick. He looks quicker than he's been. I'm excited about him."

Barber is the nominal starter in a time-sharing arrangement at running back that includes Felix Jones and Tashard Choice. If form holds, Barber would receive about 15 carries per game.

Based on his performance in the last two seasons, that may be too many chances. The trend arrow for Barber points downward.

In his first three seasons, Barber averaged 4.54 yards per carry. In the last two seasons, he has dropped to 4.02.

Of the 22 runners with at least 200 carries last season, Barber ranked 16th in yards with 923 and 14th in average at 4.4. When the Cowboys returned to the playoffs last season, a battered Barber was spent. He gained only 18 yards on 11 postseason carries.

Injuries contributed to the drop in production. Barber was not the same last season after straining a quadriceps muscle in the second game. He had 203 yards and a 6.3-yard average in the first two games and 729 yards with a 4-yard average for the remainder of the season.

That injury has taken on a mysterious quality.

By definition, a strain is a tear. The uncertainty centers on just how severe the tear was.

Barber missed only one game, suggesting it was a low-grade tear. Peete said this week Barber incurred a more severe tear that probably should have kept him out for six weeks.

That leads to two versions of reality. Despite having depth at the position, the Cowboys stayed with an injured back who should have been on the sideline. Or the club is revising history to rebuild Barber's confidence. The later scenario is more plausible. "