SAN DIEGO -- Cowboys owner and general manager Jerry Jones said he's not concerned about running back Felix Jones.

Jones' roster spot has been a topic of conversation because of his failed conditioning test, two drops in the preseason and, at times, slugglish play.

"That’s a ridiculous thought,” Jerry Jones said on KRLD-FM Tuesday morning. "I’m not worried about him at all. From what I’ve seen out there, he’s got a chance to have a big year for us."

Jerry Jones should be worried.

Of the three players who failed their conditioning test -- Brodney Pool, Andre Holmes and Jones -- the running back's failure was the worst. Jones is entering the final year of his contract and needs to not only show the Cowboys, but other NFL teams, that he can be a productive player.

Failing that test wasn't a good start.

The excuse was he was dehydrated or he didn't work out with the team because he was recovering from offseason shoulder surgery.

The Cowboys are counting on Jones to make an impact with the running game, especially with durability issues surrounding starter DeMarco Murray and some unproven backups in Phillip Tanner and Lance Dunbar.

Jones hasn't missed any preseason games, but doesn't run with a burst or elusiveness on a consistent basis. During Monday's practice against the San Diego Chargers, Jones reached the second level on a carry and made a juke on a cornerback, who didn't flinch.

Injuries to his toe, hamstring, ankle and knee might have taken a toll on him.

Jones is listed at 215 pounds, which is a good weight to absorb the pounding of the NFL, but should he be lighter? Jones was near 210 pounds earlier in his career, then bulked up.

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"I think he's going to be fine," running backs coach Skip Peete said. "He's working himself back in. He didn't have the opportunity to go through OTAs or any of the minicamps and the first day of training camp, a couple of days everybody started because of the conditioning test. He knows he's working and what he needs to do in order to get himself prepared to play. I'm excited for him and he's working every day and he's getting better every day."