Keane's on & off-field volatility - ie. where he did seek to end a player's career, in a premeditated act of revenge - never stopped him from being the sort of dominant captain others should aspire to be.
Barton shares a few of Keane's traits. He plays with drive & purpose and leads by example, and he expects others to follow suit. He'll lay harsh criticism if they don't, and like Keane he's seen as being 'politically incorrect' or too forward/straight talking in the media. Barton is a breath of fresh air in this sense, and to compliment the attributes already mentioned he's a good player.
And what's often not spoken about, and this is often forgotten about amidst his reputation for being a thug or as others have cited 'a complete ****ing mentalist', is that he's an intelligent player going forward - off the ball that is. Barton, during his career at City, put himself in too many scoring positions over the course of his journey there and as such he couldn't be labelled as a player that a hit a purple patch of form - ie. goals from midfield - ala Parker prior to moving to Chelsea. It's an indication that he reads the play well and anticipates when & where a '2nd chance opportunity' might arise in & around the box.
It doesn't bother me in the slightest if he lays the occasional headbutt, or any other act of aggression in the heat of the moment. Like Keane he's a passionate individual come matchday, and of course out on the training pitch as well. As such these mind-blanks, or flashpoints of craziness, are the by-product that comes hand-in-hand with this sort volatility. When the inevitable first flashpoint does arrive i hope he doesn't get shouted out of town - by the 'do-gooder' types who first jumped on the Anti-Bellamy bandwagon when the so-called Welsh dwarf by their own estimation publically embarassed the club when he justifiably called the manager a prick when substituted, when a match was there for the taking, for reasons that were not football related.;
I find your comment irrelevant when in it comes to the captain issue and this is based on Keane's aggressive/in-your-face leadership style, and i do think these type of dismissive/shallow remarks originate from a 'moral high ground' train of thought.
Keane did his assaulting on the pitch. Barton in the past hasn't. That's not captain behaviour.