Two goals in as many minutes in the second half secured the points to move Howard Wilkinson's men out of the Premiership's bottom three.
But it could have been a different story had Simon Davies clipped our best chance a yard the other way minutes before Sunderland opened the scoring.
Glenn conceded: "I didn't think we played at our best but the key moments were when Simon Davies nearly scored, perhaps should have done, and then their second goal.
"That was a poor goal to give away and it came too quickly after the first. I felt we might be able to go up a gear after we went a goal down but the second one went in very quickly and that set us back.
"We came here and felt we would have a battle on our hands. We nullified it until half-time but what we didn't do was step up. There are more gears to us and we didn't show it.
"We didn't perform at our best, didn't get the ball down and play anywhere near like we can and in the end, when you play like that away from home, you'll more than likely get beaten."
Glenn Hoddle, while disappointed with our display at Sunderland, pointed out that the key moments went against us at The Stadium of Light.