Bill Belichick may have taken a jab at John Harbaugh in the form of offensive lineman Cameron Fleming.

On the first play from scrimmage in the New England Patriots’ 30-23 win over the Ravens on Monday, the Patriots employed an extra offensive linemen in Fleming, which required the referees to declare Fleming’s eligibility.

“71 is eligible, 71 is eligible,” the referee announced on the loudspeakers.

Patriots make the referees call eligibility on the first play. "71 is eligible, 71 is eligible."#MNF #Ravens #Patriots — Henry McKenna (@McKennAnalysis) December 13, 2016

Patriots come out on offense with a tackle as an eligible receiver. Belichick just messing with John Harbaugh. — Michael David Smith (@MichaelDavSmith) December 13, 2016

Fleming often reports as an eligible receiver for the Patriots. They use him as a sixth lineman in their power formation between five and 15 times per game.

But the sound of a referee declaring a player as eligible harkened back to the AFC Divisional Game in the 2014 playoffs when the Patriots employed trick formations which stumped the Ravens. The Patriots’ formations, which confused the Ravens about which receiver was and was not eligible, helped the Patriots win the game, 35-31. After the game, John Harbaugh voiced his displeasure with the formations. He still hasn’t gotten over it, as he again expressed frustration last week.

Was Belichick poking fun at Harbaugh’s complaints when he put Fleming on the field on the first play? It certainly seems like a Belichickian thing to do. And the Patriots kept at it with their eligible tinkering during Monday Night Football.

The Patriots started four separate drives by declaring Fleming as an eligible receiver. Fleming was eligible 14 times in total. Because of all the work as an eligible receiver, the 317-poound tackle took a total of 18 snaps, the most he’s taken as a substitute player. He took all the snaps in Weeks 1 and 5 when he started in place of Nate Solder and Marcus Cannon.

Who says Belichick doesn’t know how to have fun?