In an interview on WEEI's Dennis & Callahan radio show this morning, Gronkowski said that he's ready to go whenever summoned, but he's always taking his marching orders from Belichick.
“It’s always up to the coach’s decision,” Gronkowski said. “I’m ready to play when my number’s called, whenever they want me to go in. I mean, it is preseason, we’ve been practicing hard, we’ve been going against each other. We had great practices with the Saints; it’s been going well.”
The good news is there isn't anything keeping Gronk from playing in preseason games outside of the coaching staff. It's a trend we're starting to see more and more - teams just aren't risking losing players in a game that doesn't count. He's still the top TE available in fantasy drafts.