This may have been mentioned earlier, but worth repeating now. I had a chat with a Tuck student a few weeks back and he mentioned that because the adcom wanted to keep it fair for incoming students this year, they are keeping their class size constant at 280 (so that will be the 250 student intake for this year + the 30 students deferred from last year).
Please note that this was from a Tuck first year STUDENT during a coffee chat (not an adcom or anyone who is actually involved in the admissions process).