Why re-sign him now?
Brooks would be currently at his lowest value, so signing him now would have the least impact on our cap.
If the club's power brokers believe he can produce quality football in an improved side not it would make sense to extend him it before he can showcase this to other potential suitors. Additionally, one can look at the other options likely to become available and assess if there likely will be a better alternative. If they do not believe there will be then again signing him now would make sense.
As for what has he done? I guess you will think all evidence would be 'fanboy b.s.' but I read this on another site today.
"And yet: if you factor in the meagre amount of ball he gets compared to other halves, his return is actually pretty good. His try assists are middle of the road, but when you factor in that the Wests Tigers are far from middle of the pack, it’s probably an overperformance. His linebreak assists are elite, suggesting that he’s putting blokes through gaps, but they aren’t capitalising on it.