A Callum McGregor own-goal was the difference between the two sides as Gers claimed yet another Scottish Premiership victory.
Speaking to RangersTV, Gerrard said: "I am really pleased and proud of the efforts the team have given and their application. but, I think it was a story of two halves.
"We were second best in the first 45 and I wasn't really happy with our organisation or us in possession if truth be known.
"We couldn't really get a foothold in the game, but you have got to credit Celtic, I thought they were really good for 45 minutes.
"It was a massive improvement after the break, up until the sending off. It felt like we were getting up to the ball quicker, we were more aggressive and less passive.
"We were believing in ourselves more in possession and it was a significant improvement.
"And then, obviously, the sending off is a real, big moment and we were favourites to go and win it from there.
"I am satisfied with the result and the three points. I'll analyse our performance and I'll go over it in fine detail as to the reasons why we weren't ourselves in the first 45 and why we improved more.
"Of course, we will definitely debrief that situation, but in football, I would much rather win and not be ourselves or win ugly and be a winner rather than like it was in the cup final where everyone was saying how pretty we were and our style and how much we dominated the game.
"But we came away with nothing, so over the course of the season, I think the players have more than enough in the bank in-terms of praise and how well they have looked.
"But we are at a stage now going into the New Year where it is about results." The half-time interval saw Gerrard replace Kemar Roofe with Ianis Hagi.
The manager explained his thinking, saying: "It was on our mind in terms of myself and the coaching staff to make a change because we weren't happy with the front three in the first 45 minutes.
"It was a stroke of luck really - or not luck in-terms of the injury as Kemar has a niggle in his quad which we will have to assess and hope he is back fit.
"But it actually played into my hands to get Ianis onto the pitch and I thought he was outstanding in the second half.
"Ianis takes on information really well and I thought he was really brave to receive the ball in the wide areas.
"Ianis basically produced in the second 45 what we were looking for from our 10s in the whole game.
"So credit to him, but it is a bit of a blow losing Kemar."
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