Jester David
Hero
I imagine they can tweak the math all the way until the end, as they can layout and polish the book and still tweak the numbers without greatly affecting pagination.I doubt it'll be at PAX East if that's what you are insinuating. Mike Mearls answered that some of them would be going to PAX East but their work schedule wasn't allowing them time to have an organized presence or gaming there this year.
It sounds like they are still frantically trying to finish the game on time. A bunch of us on another thread were guesstimating that the book would need to be finished by the end of this week in order to release at Gen Con but some of Mike Mearls tweets insinuated that they are still in the middle of a final pass and rework on the math this week based on feedback from the private beta. Which implies they are a little behind.
Heck, they could continue to tweak after sending the PDF to the printers, as the printer will send back a proof and WotC can check that and send a revised PDF with some tweaks.