From what I saw, JD and Wandale were pretty much the exact same size. A few years ago, I had a class with JD and he couldn't have been more than 5'8". Probably more like 5'7" 170 if I had to wager. With that said, I think a lot of the athletes are generously listed when it comes to their heights and weights at NU, even the taller guys.
And, I'm not saying that JD and Robinson (or any players like them) had no place on the team either. They were great players and would have been able to have been better utilized if there was more around them. That's not their fault, this staff has ultimately failed at getting more (and bigger) offensive weapons on the field up to this point. Hopefully that's changing now.
For the record, NU needed more size. Although this notion that they should abandon the Duck-R/small shifty receiver seems a bit short-sighted to me. Why can't you have both? Pretty sure the most successful NFL franchise of the last 20 years has pretty much always featured some small quick guys (Welker, Edelman, Woodhead...etc.) as fairly significant parts of their offenses. And I'd venture to say Bill Belichick knows a bit more about football than any of us do.