Sounds as if the Cats had their measure. Prismall did get injured, though. And something also happened to Djerrkura, too, IIRC. I guess a footballers' life for them just wasn't meant to be.
He did. Injured his knee during the Qualifying Final in 2008. Frank Costa then publicly stated he would be offered a new contract at either the Grand Final dinner or Best and Fairest (can't remember which). This is a guy who had very few actual written contracts with people as you didn't need them if he gave you his word. Plus they knew the first year would be a write-off while he recovered from his ACL injury. Pretty good show of loyalty I would have thought.
Prismall chose to ignore this and left for the more lucrative pastures of Essendon. Strangely enough they eventually delisted him too at the end of 2012. However this was not his fault. Just ask him.