Salford are most likely, in an effort to free up as much cap & move players not in Nobles long term plans .
This Fella would be able to tell you. I would guess. ( Whether - a performance criteria was a standard inclusion in RL -SL , contracts )
Given that a Professional RL player once signed is a employee , and most company standard form contracts include a performance criteria.
but how you would measure - objectively that a player has contravened by not playing well enough?
most players who are ' sacked ' are due to a misconduct - IE criminal offense - that means they are not at liberty to play or have brought the name of the club into disprepute.
Nearest I could find was Bradford 2009 ' sacked Tame' Tupou for being unable to train for 26 weeks in any 12 month Period .( above )