Derek Carrier has had to be persistent and patient during his short professional career, waiting for his opportunity.At little Beloit College, Carrier was an outstanding receiver, setting school records with 189 catches for 3,111 yards and 29 touchdowns. But the 6-foot-4, 241-pounder from the Division III school went undrafted in 2012. He was signed by the Raiders as a free agent, released, and picked up by the Eagles, who released him late in training camp last summer. He then was signed by the 49ers to their practice squad in September of last season and promoted to the active roster in November.But buried on the depth chart behind Vernon Davis, Vance McDonald and Garrett Celek, Carrier is a long shot to make this year's roster.Now, however, with Davis holding out, Carrier – who also was on the basketball and indoor track teams at Beloit – has had a chance to show what he can do, and the 49ers have been pleased with what they've seen.It now could be an interesting battle in camp for Carrier to prove he belongs on the opening-day roster.Recently, the San Francisco Chronicle's Kevin Lynch made Carrier his No. 1 pick on his list of 10 "sleeper players" going into 49ers...