So, I've been thinking about this a lot lately.  There is a need to preserve the ability for players to change their squad power (for things like achievement hunting and such), but still maintain a fairness in tournament play.  So why not have the squad power used for tournament match making be based on an average squad power used in their last 50 to 100 tournament matches - but ONLY tournament matches.  As far as I can tell, match making is based on an average of your squad power from your last X number of matches of any kind.  That allows for too much maniplation by players.  But if the average uses only tournament matches, well, its simple, fair, and would be extremely effective.