So, just for me, I always find it strange when people root out of geographical areas...
For example, my buddy Steve is a Yankees fan, a Cowboys fan and a Lakers fan...so the guy is either a total frontrunner (because each of those teams have been at the top of their sports at one time or another) or he absolutely geographically dyslexic!
I was always taught you root for the team from the place where you are from...
I was born in Boston, so I root for the Red Sox, Patriots, Celtics & Bruins. Period. I have never rooted for any other teams, even though I lived in South Florida for 35 years before returning home in Jan 2009.
The only exception is rooting for your alma mater(s), which is why I root for The U! But I also like to watch and root for BC, as well, just to keep the Boston connective tissue! The only time I don't root for BC is when they play The U!
I am sure there are good reasons for rooting for the Patriots but NOT the rest of the Boston teams, but I can't sure think of any!