I think it's less drifting and more him kind of getting sent to a magical fairyland of okama that scared him for life. It's silly and dumb but I still think we have our cool, badass Sanji. He's still smart too.
The thing I feel with Sanji is that...maybe it's because of that "Call me Prince" scenario in Alabasta, but I think there's more to Sanji then we think.