This is exactly the same thinking as me. This trade goes beyond the basketball court. Perk and the starting five can probably beat most teams with their eyes closed (slight exaggeration) they know where each other are, they know what to do, they can yell at each other and take it in a positive way to help the team out...
But their bond off the court really tightens up that brotherhood feeling on the court. So Perk having Rondo in his wedding party, being best friends with all these guys in the Boston area and fitting in with these veterans off the court really has a huge impact on that trust and committment factor. It might not be that easy to replace your brother with a 23 year old trying to make a name for himself. He could easily be quickly outcast by a team like this if things dont work out right from the start. If he becomes and outcast and cant fit in with this teams off the court swagger, that is going to greatly disrupt chemistry on the court which I am worried about.