Seems like an odd way to prove a point. I would guess it takes 6-12 months for an athlete to get their legs back. Muscles and neuromuscular response take some time to develop if dormant for 2 years and it takes a lot more than a couple months to get back to where you were. The best way to compare this would be to take a sample of similarly rated players and split them into those that went on a mission and those that didn't and then compare them. I think you would see a significant number that flame out post mission or never regain their prowess on the court.

Some bounce back more quickly than others.