Players get frustrated so I'm not sure there's actually beef there. Regardless, we know DK to be highly emotional. This works in our favor, at times. It works against us at other times (and I'm not sure it'd ever work again without Pete there, as he was the type of coach that knew how to gas up a volatile player and juice their best play out of them).
I'm not sure that Mike is especially keen on DK's type. He craves discipline and structure. His comments about the INTs and calling them "Team interceptions" leads me to believe he was not a fan of DK blowing that route and causing that second INT.
If there was ever a time I felt like DK could be traded, it's this year prior to the deadline. The Chiefs make sense, and they've got two stud guards. One of them is 25, iron-man healthy, and a top-15 guard in the NFL easily - and they're about to have to pay him. Meanwhile, at WR, the cupboard is pretty much bare outside of Rice and some younger "potential" types.
I have never wanted DK traded. I believe he's a rare type of WR - the physical unicorn. I think great teams usually collect as many "unicorn" types as they can and try to marry them into a cohesive on-field product. If they do trade DK, though, it should be imminently, and hopefully we can get the Chiefs to cough up Trey Smith and a sweetener, say a third and fifth rounder.