http://www.cnn.com/2015/03/02/us/north-carolina-armored-truck-heist/index.html
These guys were professionals. Sounds like they sabotaged Armored vehicle so it would stall out and then robbed it clean.
Well say you transition tag him and he ends up getting a huge contract that you don't want to match... Well them you just lost your chance at regaining a good compensatory pick next year by tagging him.
Franchise tag is way too much money.
This will only look bad if they can't re-sign McCourty. Other then that it is a nice cheap tag number which is a good move... If they can re-sign McCourty.