A.J. Jenkins is hoping his third team’s a charm

Entering his fourth NFL season, with 17 catches on his resume, A.J. Jenkins knows he doesn’t have any more time to develop. So the former first-rounder said he knows his time with the Cowboys better be productive, and fast. “My clock is ticking, I know that,” Jenkins said, via Todd Archer of ESPNDallas.com. “So I’ve…