Lelei has benefited from continuity of staff scheme and quarter back.
Porter has had 3 different coaches and systems and off the top of my head 6 different quarterbacks throwing him the ball (most of them being slop)
Collins was acquired late in June and didnt get any of the starters reps in camp, coming into a new system himself. Not to mention the lack of a running game.
Anyhow all that being said, Porter is the more complete reciever.