I think it's a bit premature to say Martell is a waste. He just started at WR. A big criticism of the WR room is that they cant learn the offense. Martell seems to be a good student of the game. If he focuses on learning WR skills and can shave .1 off his 40 time (so he is in the high 4.5 low 4.6 range- not impossible) I wouldn't be surprised if he sees the field a lot next year as a shifty little WR.
A 6'5" 240 lb. athlete with a 4.2 shuttle time can do a lot of things. You cant teach size.
In terms of saying he couldn't beat out Nix and that he stinks- Jarren Williams couldn't beat Rosier or Perry, now he's the starting QB. Enos seems to be pretty good and coaching QBs, so at least he does one thing well. Also, Gatewood's HS completion % is much better than Williams's 62% to 57%. I wouldnt say Gatewood's college career is a bust quite yet.