The presence of Justice Kagan

Gerard suggests Justice Breyer's absence explains the nastiness of the exchanges in Warhol (and deteriorating relationships among the Justices generally)--he "was a senior and avuncular person who liked to broker compromises. You can't easily replace the social function that sort of person fulfills." Josh Blackman says the same.

But wasn't the ability and desire to broker compromises one of Kagan's selling points, based on her time and efforts as HLS dean? Is she too young? Too junior to play that role on the Court (she is the median justice in seniority)? Too caustic a writer? Or does this involve a different type of compromise--not across ideological lines but across temperament, between two people who generally align.