Gronkowski lines up in the backfield next to Brady, then motions out to the offense's left, into the slot.
The Patriots spread the field again. This time, Gronkowski is situated in the middle of the three receivers to the right side of the offense's formation, again in the slot.
Spread again (albeit with a back kept in). Gronkowski is now the boundary receiver; you'll note him lined up against a cornerback at the bottom of the frame.
In another spread formation, Gronkowski is again the boundary receiver, but this time to the left side of the formation. He's at the top of your screen.
In a more traditional formation, with the quarterback under center, Gronkowski is kept in-line to block, but his hand isn't in the dirt at the snap, keeping the defense thinking.