I think players who RS progress better over the long haul, cause they have the possible extra year. But this was always the way EA had players progress, atleast from what i can remember. I had a sticky situation in my OD. I recruited a 4* ATH who i put at CB, he has 93 speed which my team lacks especially my DBs. I had to decide RS him and he'll be better overall as a player in a couple seasons or not RS and it helps my team now. I ultimately did not RS him and he's #2 on my depth chart at CB.
Maybe its to keep guys from padding stats? But it can be annoying when i have a breakout year with a player stats wise and he doesnt progress as much as he probably should. I honestly dont know how it works or the logic behind it.