"It is nothing personal" is usually one of the most blatant lies. It always is, and at the same time it isn't. I try to judge people simply based by the quality of work they produce, despite spending a lot of time with them we are not married. So nothing personal as lond everybody acts as professionals and adults.

That being said, most political office stuff is very much personal, at least for one party involved. And than it gets nasty. And yes, with review processes being incredibly intransparent, without a real chance for the reviewed to defend himself, bad reviews are an easy way to get rid of people.