Washington's injury woes at the quarterback position continued on Monday night.
McCoy managed to limp to the locker room and was ruled out by the team before the second half began.
"This is a tough blow," Gruden said. "Losing Alex is one thing -- he's a great leader, a great quarterback, put a lot of time into him. And then Colt finally gets his golden opportunity, and he gets kicked in the leg and breaks it. So, heartbroken for both those guys, really."
Mark Sanchez replaced McCoy under center. Sanchez, who last played in a regular-season game in January 2017, completed 13 of 21 passes for 100 yards and threw an interception.
McCoy was a perfect 4 for 4 with 50 passing yards on two drives at the time of his departure.
"Mark's played a lot of football, he's won playoff games," Gruden said. "He can function at quarterback. We can get some things done.