Labour conference is surprisingly even-tempered. Why?

Why does Labour conference feel so even-tempered so far? In previous years the answer would be that it has been stage-managed to the hilt and all frontbenchers programmed with the lines to take. But this year the party’s conference strapline is ‘Straight talking. Honest politics’ and frontbenchers aren’t being sent daily lines to take, so even if they wanted to be on message, they couldn’t be.