It is highly unlikely that Craig put on 10lb of lean mass between fittings. I also highly doubt he lets himself fluctuate to that degree considering he is an avid weight lifter. Even a limited maintenance routine would spare that kind of loss. Do you realize how much mass 10lbs of muscle is? Go stack 10 lbs of lean chicken breast to get an idea. Craig would have to totally stop weight training for a long time to lose 10 lbs of muscle.
It's a pretty simple equation, I think. Ford made a rare mistake and didn't totally control the QC and design of these suits. The O'Connor was built for Craig. It fits like crap. A Collar gap on a 5k bespoke suite within a film noted for the clothing? Yikes.
Actually thats completely possible especially since he is a weight lifter. Look at his size in Casino Royale as compared to quantum of Solace, in the latter he is still muscular but you can see that he has lost weight. Plus as anyone who works out regularly knows if you stop lifting for a while or go on a cutting phase you can lose 10lbs of muscle. I myself have gotten measured up for a shirt then gone to the first fitting with10-15 additional pounds (lucky Mina at NSM didn't attach the sleeves of my shirt yet or there would have been an issue lol). It wasn't that i stopped working out it was just that it was the time of year when i switch from high repetition cutting exercises to heavy weight bulking ones. Even when i enlisted for National Service in Singapore i managed to lose muscle mass just purely because of the type of activities we were doing i.e we didn't need to bench press 270 pounds but being able to do 100 push ups helps, but it came back very fast when i started lifting weights again. I do agree though that for bond the clothing is crap but i just saw the movie and besides the collar gap in SOME scenes the fit is not that terrible (short pants/short jacket put aside).