Speaking to Mediaset Premium and Sky Sport Italia, Spalletti surprisingly commented on the gulf in class and playing style between his Inter and opponents Napoli.
The former Roma manager claimed he is unable to improve his team, which "don't have much quality".
"I've worked with this team every day and I think there is simply a lack of quality," Spalletti said.
"Napoli have quality, we don’t have much."
"We were solid, we allowed very little and were always a team, of course, but when we talk about quality, I say the difference between us and Napoli was visible.
"I repeat, I don’t think that I can improve this performance with work in training. I’ve been trying to do it all season.
"We have never played these great games where we pass the ball around quickly and with quality. Today we won back the ball five or six times and could’ve hurt them, but we didn’t.
The 59-year-old Italian bemoaned his side's lack of consistency throughout the season and suggested expectations for them are too high.
"In general, we've not played great football this season, because I don’t think we have this kind of quality that people seem to think," he said.
"If we want to take the game to the opposition, we have to pass it around quickly and in short spaces. Instead, tonight we passed it back to our goalkeeper too many times.
"If you have quality, like Napoli do, you pass it between the lines with quick give-and-go moves. We tried that, and most of the time lost the ball.
"Napoli have a lot of quality, but we don’t have those characteristics. I still have to see this supposed quality, because I don't see it."
"That's what we're like, I'm afraid. At times we are right in there and have the right attitude, at others we lose that and I don’t like the lack of consistency.
"We can’t build on it when we go forward and then back, because I can't tell you what we’ll be like next week.”
He also discussed Inter's recruitment on Rai Sport, perhaps with a message for club owners Suning Group and director Piero Ausilio.
"Borja Valero is good at recovering the ball. Rafinha played in his position and he's doing well, but we must not put too much responsibility on his shoulders.
"Don't forget in January there were a dozen names circulating and in the end we only managed to sign him."