The French midfielder helped Arsenal keep a clean sheet against the champions and was praised by Arsène Wenger for how “convincingly” he marshalled David Silva.
Sunday was the Gunners’ third consecutive shutout and Ramsey believes Coquelin has played a key role since returning from a loan spell with Charlton Athletic.
“He has done well,” the Wales midfielder said. “He’s at that age now where he understands the game a lot more and he has done really well in the last few weeks.
"It is funny how quickly things can change in football. One week he was on loan at Charlton and then he comes back in and he has been in the team every week. He has done a very good job defensively for the team.
“He wins it back, keeps it simple and just keeps things ticking over. Hopefully he can build on his performances that he has been showing of late and he has got every chance of turning into a top defensive midfielder.”
Arsenal’s commanding win at Etihad Stadium closes the gap on Manchester City to eight points and Ramsey is confident it will give the Gunners a boost in their top-four challenge.
“It was important to win because all the other teams won,” he added. “The pressure was on us. City have made their place a fortress over the years. Not many teams come away with three points so we are delighted with the way we went about it.”Copyright 2017 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source