His stats shouldn't drop. He's only been out of the game for 1 year, and he's still actively playing a sport and in his prime. It's not as though some 35 year old retired last year. If it's fair, his stats shouldn't drop.
I'm sure if he came back to league, began training a bit and played a few games, he'd be back to his best in no time.
Well, if he needed to play tomorrow, he would've trained in advance, so if this begins during Summer, everyone would go bad because they've not been doing much in the offseason and had little match fitness.