Not easy at all, for anyone. RJ was an exceptional college player (and maybe will be again next season!). However his exceptionalism lay almost entirely in his athleticism, as opposed to his playmaking or cerebral knowledge of the game. He feasted against many college teams and in many match-ups based on his physical ability and way the staff chose (wisely) to utilize him.
However from an NBA standpoint, his athletic gifts are not enough to move the needle in the absence of the other things that are required at that level and when the offenses will be very different.
As noted above, in that respect he is very much like Ponds who was an outstanding college player (worth the price of the ticket to see him play many nights) but never quite acquired the other skills that might have helped him succeed at the next level.
It's just one of those things that shows you how very different the NBA game is from college. Some guys who don't produce much in college are high picks for the NBA based on age, potential, and how the NBA thinks they will fit. Some guys who are highly productive in college never get a cup of coffee.
Sometimes it turns out the NBA is right and guys who were great in college get a cup of coffee and then go play in Turkey. Sometimes the NBA is wrong and guys it didn't think would make any noise wind up playing for a long time. Marcus Hatten never even got a cup of coffee. Walter Berry didn't make any noise in the NBA. Steve Blake (a 3 point shooting stiff from Maryland) played in the league for like 15 years.
I think that sometimes a big element is character, which is why Brunson and Champagnie outperformed their draft slots (Brunson by a lot). And I think Walter Clayton may very well do the same thing, and I'm hopeful about Zuby.