I think there are only two reasons to drop Watts at the moment. One is to give him some confidence, and the other is to punish him (euphemistically, to 'teach him a lesson'). Given we're playing Gold Coast next week, I'd say that rules out the former.
Tallies of 3, 5 and 8 goals* isn't knocking on the door?
You might argue against playing Newton, but to suggest he isn't 'knocking on the door [...] like Gysberts and Wonaeamirri did' seems obviously wrong (unless you're suggesting Newton is knocking harder than they did).
*In addition to being named by the Coach as Casey's best player last week, giving off goals, etc