I actually think Brooks compliments the Knights better than Hastings especially with Ponga in the halves. Brooks personality is a follow orders style who would mould into the team which in their team dynamics & personalities forming could be important.
Hastings is a controlling half but not a creative one. 63 NRL games, 3 tries & 22 try assists just wouldn't work in the Sheens/Benji game play. That's why it was lock or nothing for him here.
It wouldn't surprise me if O'Brien, Gamble, Elliot, Hetherington, Hastings and few others clash during the year. It's big reason Klemmer is leaving is the team/coach dynamics. Knights have some hot heads who aren't afraid to clash with team mates so the dynamics could be very interesting.