Allan performed for half a season at Dundee United and one and a half season's at Hibs. At West Brom, Celtic and Rotherham he has done zero. He's not a young prospect in footballing terms anymore, and has wasted most of his career on benches, in reserves and chatting on phones to pretty awful agents or whatever other cretins have been advising him.
I can't see him fulfilling anything like his potential now, which is a shame because he's some player. The return Hibs have got on Allan's sale is probably one of the great bargains in Scottish football, and we'd be pushing our luck to think we'd get a similar one in a second spell.