So you only portal if it's a top 5 or 10 guy? What if the guy you have is 30th or 40th at his position? You don't grab the 25th best guy, if you can?
Do you want a guy in as much as possible if it means he can't give maximum effort all of the time or if you have to artificially slow the pace of the game to keep guys fresh? You saw my post about the player of the year semifinalists. Why didn't more of those guys play bigger minutes? Shouldn't they all have played 38 min/game? How did UConn win a NC with nobody averaging over 30 min/game? How is Houston a 1 seed with their leading guy averaging 32.6 min/game and only two guys playing more than 30? Alabama had one guy at 32.6 and nobody else over 30. Purdue is similar. Kansas was the exception amongst the 1 seeds with 4 guys averging over 30 and one guy at 35.
It just isn't true that elite guys demand minutes like you claim they do. They want a major role, but that doesn't have to mean 35 min/game. And even more, they want to win. A guy would rather go 35-2 while playing 32 min than be 25-12 at 37 min. If he wouldn't, then he sounds selfish, and I don't think that we want him.