I think you mean "regress." Sorry, that's a personal pet peeve of mine.
Other than that silly nitpick, I'd say you're being a bit harsh on Nelson and McRoberts. I think we're asking them to be more than they really are. Nelson is not a go-to offensive player, and we've basically been asking McRoberts to carry the offense. Both are inconsistent shooters, neither has an established post game, and neither is a good free throw shooter. So expecting them to score consistently just isn't a fair expectation.