Brady, Gronk, James White and Bob Kraft were all at Fenway Park for the Red Sox opening day ceremony -- where Tom proudly displayed the Super Bowl 51 jersey he just got back.
That's when Gronk jumped in -- stole the jersey and tried to run away. He was caught from behind by Tom Brady.
Time to work on speed drills, Gronk.
[H/T to our friends at NESN for the video]