I don't suppose you've considered that, if we didn't play so fast, maybe Cousins wouldn't be the last player down the court as often?
I've considered it. But given that we play 4.5 possessions per game faster than the average team, and that Cousins plays about 72% of our minutes, that translates to about 3.2 extra trips (one trip = one back and forth) per game. Do I believe that if he played 3.2 fewer trips per game Cousins would be among the first players down the floor most trips? No, I do not. So yes, I've considered this hypothesis, but I've rejected it as a reasonable explanation.
Also, why would Collison being our best bench player mean that he has to be played in conjunction with two other guards all the time?
That's true, Collison being our best bench player does a better job of explaining him being played out of position at the SG so much, and not the three-guard lineups.