I don't think Cork is ahead of him at RB, Cork was moved there because he was already on the pitch. I'd be surprised to see him starting in that position ahead of (a fit) Richardson.
The exclusion of Richardson is quite strange, as I too thought that he was very good in the Championship, but if Adkins & Pochettino don't think he's up to the PL then I trust their judgement over mine.
I really like Richardson as well. He doesn't really excel at any part of his game, but he's a very good all-rounder. On Cork, though, I actually think he's an excellent RB. Almost as good as he is at CM.
I agree about Cork, he had a terrific game at Wigan in both positions. Richardson is cetainly a decent player but he hasnt had much of chance this season.