User blog comment:IceFireWarden0/Speculations for Season 11/@comment-92.25.204.97-20130702121844/@comment-5259531-20130702153003

The inclusion of Donut depends on the availability of his voice actor, Dan Godwin, as he doesn't actually work within RT and during the Blood Gulch Chronicles he recorded most of his lines from home, unlike the other voice actors. I'm guessing Dan has been less available during the past few seasons, hence Donut's sporadic appearances in the series. I do want him back for good though, or at least an explanation for his absence.