A product of the Real Madrid academy, Alonso also played a senior game before leaving the club for Bolton Wanderers in 2010.
"One of the biggest losses that Chelsea have had is John Terry", he told Love Sport Radio.
"It's only halfway through Sarri's first season but the worst thing I can say is it looks like he has turned Chelsea into Arsenal".
Asked if this defeat made him fear that his style of football can not work at Chelsea, Sarri replied: "No, because today I didn't see my football".
It began badly as they were caught napping after just four minutes.
Defender Azpilicueta, who was given a torrid time by two-goal City winger Raheem Sterling, said on the club's website, www.chelseafc.com: "It's hard to find the words to describe my feeling after the game".
Chelsea are making a nasty habit of breaking records for the wrong reasons under Maurizio Sarri, with time running out for the Italian to avoid becoming the latest coaching casualty at Stamford Bridge.More news: Second Trump-Kim summit confirmed for end February in Hanoi
More news: El Paso mayor challenges Trump’s SOTU claim about pre-wall crime rate
More news: Gay serial killer Bruce McArthur given eight life sentences
Most of the damage came in a whirlwind opening 25 minutes, with Aguero hitting his first two of the afternoon between strikes from Raheem Sterling and Ilkay Gundogan.
"If the president calls I'd even be happy, seeing as I never hear from him", Sarri said.
It is understood that the Blues want Sarri's assistant, Zola to handle the club as caretaker for the rest of the season if they decide to axe him.
How does a player with the medals and statistics of Aguero sometimes slip under the radar when people discuss the greatest players of the Premier League era?
Silva said: 'Of course it is better if they lose some points but I think all of us, not only the manager but all of the players, have been saying to focus on our job. They have since lost seven out of 21 in all competitions.
Among these players, Aguero has the lowest minutes per goal or assist ratio with 85 and he narrowly beats Henry's figure of 86.
"The Arsenal team that has got battered away from home in the last seven or eight years because they have been too weak".
"We had only to stay in the match but the reaction was not good".