It really doesn't. Being heavier makes everything higher impact and from playing a lot of sport for my entire life and at reasonably high levels, you lose conditioning and fitness far faster than you lose the ability to perform at a high level. Your muscle memory and ability to do a lot of things remains and you can do many of the thing you could previously do, you just suffer for them through injuries.
This is part of the reason injury hit players do exercises to strengthen around joins, strengthen supporting muscles and fix imbalances. These all help to prevent injury and unless you are super super disciplined, a lack of playing time will result in your body losing that conditioning, stabilisation etc that helps stave off injury.