Problem with Nelson is that he's a HR hitter.
Either he'll get you that 3 for 125 and a TD game, or he might get you 1 for 15 yards. You can never tell.
AJ is much more consistent... but lower ceiling, it would seem.
What do you need more? Consistency or a HR hitter?
Just someone that can put up 8-10 points. I have Marques Colston as my second receiver and he's been averaging like 5-7 with a big game here and there. The HR hitter/Consistency thing seems to work but like I said, I compared there schedules and Nelson vs weaker teams is when he puts up higher points... And his schedule has some easy teams left where as AJ Green still needs to play Pit and Baltimore (x2).