I assume you're right re it being about scrummaging but is Kepu really stronger in the scrum than TT in 2019?? No doubt Kepu put in a much better scrum performance than TT did against Samoa, but other than that I would say hands down TT has been more effective in the scrums this year than Kepu, who seems to have started a slow decline and I dare say his best days are gone. and that's not even taking into account his general play around the field.
I'm hoping it's just Cheika's way of making it clear to the front rowers 'you get your set piece right first and foremost or your not in the side'
Kepu is Kepu he is our most experienced THP ever, he is effective at scrum time, and has been all season and has been effective around the field.
I think TT's lack of experience at handling and adapting vs Samoa is the issue, as Cheika said above, they went for experience