Chicago's Daniel Brown recovered the ball in front of Beckham with just over a minute left in regulation. Beckham appeared to hesitate before diving to the ground for the ball. Safety Curtis Riley also missed a block, allowing Brown a free run at the ball.
Chicago was able to tie the game and send it to overtime before losing 30-27. Despite the final result, the play left Beckham open to criticism.
"That's fine," he said afterward. "It was a great kick. Sometimes, somebody makes a better play than you do. I can dive in there and still not get the ball. It was a very tough call. Nobody should ever question my effort or my heart. That's the last thing you can do. You can question me as a person, as a man, whatever you want to do. But my heart and my effort can never be questioned -- ever."
Beckham seemed surprised at the blowback from the play. He was asked earlier in his news conference why he didn't dive for the ball in such a crucial spot. Was the ball too far away?
"That sounds like a question that was you just asking to ask, kinda. You know?" he said.
It didn't seem to be a problem in the locker room, where the Giants enjoyed their third win in four games. Beckham remains a popular presence and even addressed the team pregame and at halftime.
"I never question O's effort," wide receiver Russell Shepard said. "Never question his heart. He wants to win. He's a big reason why we won. He gave us emotion. He gave us leadership. He said some things to us pregame and halftime that pushed us over the edge."
On his halftime speech, Beckham said: "Honestly, I addressed the team at halftime, and I told them there's just something I had to get off my chest. I love these boys. Every time I put on a helmet, whether it's practice or it's a game, I'm going to give it my all, and I feel like I owed them more, to give them all of me and whatever that entails."
Coach Pat Shurmur said he didn't see the onside kick play closely. It was on the other side of the field. He reserved comment until he watched the tape of the Giants' victory.
It was in part because of Beckham's contributions. He threw a touchdown pass and caught another. His 49-yard touchdown pass to Shepard was his second passing TD of the season. His 1-yard catch on fourth down late in the third quarter was his sixth touchdown grab of the season.
"So we drew a play up. I told Bennie [Fowler], I don't care what happens, I'm going to throw it to you, and they double-covered him, and this grown man from LSU who I've played with for a long time, I saw him down the middle of the field, and I was like, this can't be real, and I just launched it to him," Beckham said of his touchdown pass. "It's all good. He wasn't supposed to do that, but he's just playing football, and he came up with a huge play for us. Very, very, very big play."
Beckham finished with three catches on nine targets for 35 yards in the contest.