Online team play is an excellent idea and probably the most fun part of all the NHL games. However, I always wondered why there was no idle player boot in OTP. Now I understand that it probably wouldn't be fair to boot someone from a ranked game, if for whatever reason had to put the controller down for a minute or two.
In this instance I believe instead of leaving an unattended player sit on the ice, automatically send him to the bench after a whistle and have an AI skater play that spot until the person returns to their controller. Pressing A or whatever button will return the player to the ice on the next whistle. So not necessarily an idle boot. Which most are familiar with in titles like Battlefield 3, where after 300 seconds, you are kicked.
To prevent those from trying to take advantage (sitting the bench the entire game to get games under their belts), simply kick the person after either an entire period goes by or after a certain amount of time passes.