I think his personal relationship with DS helped him get through previous difficult spells. I get the impression that SG is more hands off with players and expects them to show mental strength. The last couple of months have seen a different Ollie Watkins: low on confidence, apathetic about matches, and even his usual tenacity in chasing things down is now reducing.
Like all strikers, he's a selfish so and so: this is manifesting itself in ways that are proving unhelpful atm. I don't know how SG is meant to manage Ollie's confidence: other than hoping a ball bounces off Ollie's arse in a match and convinces him he can score again.
If Ings can do the work off the ball, fitness permitting, then he'll start over Ollie again Newcastle.