Much better than the staff pukes that ran the Pentagon under Obama.
That's really a key point. The SoD has more influence than anyone else in determining flag rank promotions. Mattis knows the warriors from the SJW weasels, and would be instrumental in ensuring that the warriors -- and sharp REMF types not bound by SJW conventions -- rise to higher leadership positions.
He'd also likely have a good bit of influence in helping select service heads -- Secretaries of the Navy, Army, and Air Force, and will prefer those who focus on military effectiveness/efficiency versus social justice.
I don't care how much experience he has in procurement, etc.. What is needed is someone who is a good judge of the character and intelligence of others, because he can always bring on the right procurement/contracting experts.
This is an absolute home-run pick that I'd never have imagined prior to the election.