Yeah, that may have been a stretch but he was one hell of a dirty cop this past season. He basically had his partner's house burglarized and his partners son's life in danger as a result. In real world cop society, his arse would be grass and many cops would happy to be the lawn mower.
That's what I'm saying. I mean everything we're taught about his character in the first 2 seasons, all the way up to him turning in John for having a pain pill addiction because it was "the right thing to do." I mean, he goes from integrity being EVERYTHING, doing what's right, even if it meant turning on his fellow officers like Serpico, to 2 full seasons later he's banging cholas and then punking her brother while kind of subcontracting them to do his dirt.
and that was just the tip of the iceberg for how bad his character was becoming. If there would have been a season 6, he for sure would have been in plain clothes, wearing a black leather jacket and skull cap, driving a tricked out black monte carlo with hydraulics and training some punk arse rookie in the art of robbing drug dealers while simultaneously forcing him to smoke sherms. Oh and he'd be into the Russians for an unGodly amount of money while trying to sell his partner to the same essays that lives with the chick he's banging while he "figures shite out."