Kirk Cousins led the Redskins on an excellent drive late in the first half of Saturday night's game in Philadelphia, putting the Redskins at the seven-yard line with six seconds to play.
What happened next is hard to explain.
"Six seconds left, we were going to throw a fade to Pierre Garcon," Gruden told CBS' Evan Washburn. "I have no idea why Kirk took a knee. I'll have to find out at halftime."
"There was a lot of confusion with what the playcall was and for lack of a better word, I just had a lapse in my decision-making and instinctually took a knee when I should've thrown the ball away to stop the clock," Cousins said in his post-game press conference. "We were very fortunate it didn't end up hurting us."
The lapse didn't end up costing the Redskins, who dominated in the second half en route to a 38-24 victory, clinching the NFC East.