He wasn't really that top line and wanted by many SL clubs at the time!
Not really that top line other than being a big part in Hull's CC final win over Leeds you mean?
He was prior to that and still is a quality SL player when on form (which is most of the time). It's unusual for such a player to go down a league and then back up within the space of a season. Perhaps understandible if its a player long-term-loyal to that club and they stick with them throughout a drop and help them back up again but that wasn't the case. The case here is a very rare event. Considering Brough seems to like spending money (and presumably therefore getting paid a decent salary) and he also doesn't seem to mind which club he plays for it seems odd he was so seemingly altruistic (he took a drop in salary) towards Castleford.