No he isn't rotten for Leeds. He's decent for Leeds. English Championship team of the year last year.
He's just one of a bunch of centre backs that Scotland have available (Devlin, Souttar, Hanley, Lindsay, McKenna etc) who are all of a relatively similar level - limited. Doesn't really matter which of these gets played but I wish Clarke would pick a centre back pairing and just stick with it. Only way you're going to get a better product in central defence is by letting a couple of those guys get used to playing alongside one another over a series of games.