In Carroll's offensive scheme, his skill set is probably best suited to split end -- outside on the line of scrimmage where he will draw double teams but will still be open for quick hitters. And he is more likely to be effective as a blocker outside against a DB than inside against a DL.
This is the position manned primarily by Golden Tate in 2013 and Doug Baldwin last season. In addition, it would allow Baldwin to move back to his more natural flanker position in the base offense. Baldwin will be a beneficiary of more single coverage and more space to get off the line of scrimmage at flanker and in the slot.
As others have said, he has proven that he can wreak havoc when moved all over the field (and especially in the slot) but I think SE is his most natural position in the base offense. The possibilities are extremely exciting.