Another point to add to the Chase argument is that when ever other teams play Cas the opposition coach often says we'll have to stop Chase to win, he's often the sole target of the opposition defence who will work on plans to stop him, as stopping him does stop Cas.
I know it is true that other top players in super league are targetted but stopping Tomkins doesn't stop Wigan, stopping Monaghan doesn't stop Warrington and stopping Roby doesn't stop Saints all the top teams have other players to distract the oppositions attention from their superstars, Chase takes all of the attention for himself and quite often is still unstoppable.
As a Cas fan I have obvious bias but I'd not rather have any other player in Super League in my team.
