The trickery — all legal — prompted Baltimore Coach John Harbaugh, confused and angry, to take a penalty to get an explanation from the officials. Harbaugh called the substitutions “deceptive” after the game, but he has since said his problem was with the officials, not with Belichick or the Patriots.

The Patriots knew they had fooled the Ravens. Vereen said, “That was the design.”

Normally, a player designates himself as an eligible receiver. The Patriots did that frequently with linebacker Mike Vrabel. The Houston Texans have done it with J. J. Watt. Vereen did the opposite and said he was ineligible, even though he lined up all the while appearing to be ready to run a route.

On the first play, however, he dropped back on a fake, and Tom Brady found a wide-open Hoomanawanui for 16 yards.

Belichick said it was situation he had seen before, though he would not be more specific. He added: “We talked about ways to put some pressure on the defense with that concept of having more receivers on the field than were actually eligible. To make them ineligible instead of making an ineligible guys eligible, to go the other way around.”

The Patriots’ offensive coordinator, Josh McDaniels, said: “Everything is a part of the rules, and if there is a way that maybe you can give yourself an opportunity to get a positive play in a different situation, it’s worth doing. Definitely have seen it before, and I’m sure it won’t be the last time.”