I think the St James Palace is a bad race to judge form on. Frankel kicked way too early and ran out of gas. If Quelley had held hold of him then he would have won by 5 lengths. Excelebration ran ok and then hacked up in a group 2, Dream Ahead is a sprinter and then won a group 1.
Zoffany loses his races himself by his attitude. He hangs and tends to pull if there isnt a strong pace so to beat Frankel doing that hes going to have to be a super horse which i doubt he is. Imo Frankel wont every be beaten because there is nothing good enough out there.
Even in the southern hemisphere all their best horses, Black Caviar, Star Witness and Sepoy racing over sprint trips. I believe that Frankel would win a race over 6f because he has tremendous cruising speed but i doubt they'd ever go that route because the prestige isnt there with those races.