Assume that he'll perform comparably to his lifetime track records within whatever disciplines you choose.
Or, simply do not play the game.
I for one do not see much of an inherent advantage either way, although you can bet that millions would/could and will argue either way.
"he's well rested" "he's too rested" "he's rusty" "he's had some time to work on some things"...
blah blah blah.
He'll prolly give up ~3 runs in ~6 innings...or, pretty much what he's done all year and the 6 seasons prior to it.
James