Yeah, we've seen a lot of loan players being recalled and sent out elsewhere recently, whether that was down to them stepping up a level or just not getting a game. Like you say, it's too risky to rely on getting a season out of a player who's performing well.
Biereth is a guy who has a lot of confidence in his own ability and is hungry to prove himself, which worked for us, but no one should be surprised he jumped ship so easily.