49ers rookie wide receiver A.J. Jenkins will need to increase his upper-body strength in order to make an impact this season, according to a report. Multiple sources told Pro Football Weekly that the first-round pick will have trouble against press coverage if he doesn't bulk up. "He hasn't looked very good," a source told Pro Football Weekly. "He displayed some flashes with a few really difficult catches, but he's also looked really bad at times and he seems to have had problems staying on his feet. "It's early. Maybe he'll show more in training camp."