ASOIAF / Game of Thrones (SPOILERS INSIDE)

[Mandalore93]

The only thing I agree with you on is that sending Theon to Balon was an all around stupid idea and is basically the only thing that Catelyn is ever right about.

It's damned if he does, damned if he doesn't in this case. Sending anyone other than the head of the lordly house would most like be seen as a huge slight. His other lords are hot heads, Roose is chosen for his cool head. At the time of ACOK, Bolton has as far as everyone knows loyally served the Starks through two generations and three wars. His methodology is surely a bit different than others, but that's honestly what makes him a valued commander in this case. We don't even know for certain that Bolton was purposefully trying to weaken the Stark cause from the start, it just seems like it. Greatjon would have been the utterly worst choice. I think Karstark would have been the best choice. Remember, at this point his sons haven't been killed and he's no fool.

Also, I'm not 100% sure on this, but I'm pretty sure the majority of the Frey host marches with Robb to Riverrun.