I don't think I've ever seen a red for a bodycheck. He did lead with his shoulder into his head though, which is a red in rugby.
The play acting from Rudiger told me he knew exactly what he was doing, his intent may not have been to fracture his skull but he fully intended to hit him.
And yet it might have worked, had Sterling's touch from Ederson's pass been better, had Rudiger not made that fantastic block on Foden.
But ultimately you're right, why change something that served you so well all season?
I wonder was it that lack of Fernandinho/Rodri that affected Stones...