The Blues lost their second game of the season against Liverpool back in September but after that they went on a run of nine Premier League matches without defeat until the 1-0 loss against Everton.
At Stamford Bridge, Frank Lampard's side were emphatically outclassed by City, particularly in the first half, as they succumbed to a 3-1 loss.
Their awful run of form has left them down in eighth in the table, and Silva was at a loss to explain the downturn in performances when asked to identify the problem.
"No, I don't understand what's wrong," he told RMC Sport.
"If I understand before, I think I could have given some advice, but that's how it is, it's football, it's the Premier League, one of the toughest championships around the world.
Though there was an argument that Pep Guardiola's side took their foot off the gas in the second period, Chelsea improved after the break and didn't concede again while scoring a consolation through Callum Hudson-Odoi.
Silva says the second half can be a source of optimism.
"You have to be careful, work harder, be stronger as a team, but I think the team is good, the second half was much better than the first in my opinion," the former PSG defender continued.
"We tried to play a little more, we managed to play. I think we were superior in possession of the ball in the second half, sometimes it does not work as we want, as we have prepared, but hey, that's how it is football.
"We must prepare for the next match when it arrives."
Chelsea have a good opportunity to get back to winning ways this weekend when they take on Morecambe in the FA Cup.