For a player in his thirties, opting out of international football essentially equates to being rested for 4 or 5 games, which can be the difference between optimum performance and sub-optimum, which is understandable when you've got a younger keeper breathing down your neck. Other players will have young families by that stage and realise their priority lies with spending as much time at home as they can. In Shay's case, it might just have been motivated by the knowledge he was slipping a bit and wanted to step aside for the good of the team.