It's a sizeable jump for Reynolds to go from WR5 to WR3. And his reps were pretty limited as a rookie. Half his snaps came in the 3 games he replaced Woods when he was hurt. But he did contribute in those three games- 8 catches (on 14 targets), 60 yards, 1 TD. 47 more snaps came in the finale vs. SF with the other backups.
I thought he looked good last preseason (4 catches, 91 yards, 2 TDs) and he did at least get his feet wet in the regular season. As far as deep threat and red zone guy he does seem like the most viable in-house candidate.