Presumebly you mean Ian Payne, who is a former Chief Inspector of the Met.
He's right. There are less officers, and May was repeatedly warned as Home Secretary that this put the public at risk, which she ignored. Services are stretched very thin, well past breaking point.
It's all very well saying that the job of the police is changing, but if there aren't enough bodies to do that job, there are going to be problems. Would more numbers have stopped this attack? We'll never know, though I think it unlikely. Without the resources and manpower though, it's always going to be a losing battle.