I seldom put anyone of value in rookie league. First, I let simmy auto-hire my RL coaches 90% of the time. So they suck. Second, in my promotion process, RL isn't needed. LoA-1, HiA-2, AA-3, AAA-4(when he's added to the 40). So the only way I'd have him in RL is because I couldn't play him in LoA. But, if I want to promote in-season, I usually give 200 AB, 20-appearances or 50 innings as minimums.