Channing Frye missed the entire 2012-13 season due to an enlarged heart, a condition diagnosed during a preseason physical. That also coincided with the first year post-Steve Nash for the Phoenix Suns and, unsurprisingly, the end of the Alvin Gentry era in Arizona. Those who have bashed the hiring of Alvin Gentry with the common phrase, "his team's get better when he left" conveniently forget to provide this kind of context to the situation.
Space in Gentry's offensive system is critical. The 2012-13 Phoenix Suns lacked it; Jared Dudley was the only rotation player consistently knocking down shots behind the arc.