Can't say I've watched Atwell. But I've seen many games with Harris and the dude is just a stud. Tall, long, fast, good hands and battles for the ball. Amazing athlete for his size. Way undersized (weight wise) for a TE. But he impacts games. Can't guard him with a LB, and unless you got some really fast Safeties he challenges them as well. That's why they liked lining him up at TE. Not a real good blocker, but he's willing and his athleticism allows him to get good position on the D player he's trying to block. Sometimes just getting in the way is good enough.
Super sleeper and we'll just have to wait on him to see how it goes. Good place to bet a poker chip, though.