The Blues are struggling in the Premier League as they sit in 12th position.
Despite a summer of mega investment, which came after an entire season of revamping the squad, Chelsea are finding themselves unable to compete with top sides.
After spending over £1 billion on players, Pochettino expects Chelsea to invest even more.
Pochettino said: “After four or five months and 16 Premier League games, it is [time to] assess.
"If we are not capable today with all the chances that we had — we need to score if we want to be in a different position in the table. If we are not aggressive enough, maybe we need to do something, some movement.
"That is something to analyze with the sporting directors and the owners and see what we can do to change this dynamic and change in the second part of the season.
“Expectation was massive. For Chelsea, the expectation is always to win the Premier League, but after is the reality. Sometimes it is a good, a reality check. We need to fight. Mid-table is our reality now.
"If we want to go up, it is not only to play well, it is about being more tough with ourselves. We are going to push the players, the players need to push themselves, and then it is a massive assessment from the beginning of the season to today, and when the transfer window opens, see what we can do.
“I'm not saying we need to ask for more players or less players, but it is to see if the perception matches the reality. If expectation is here (high) and reality is here (low), it is because we are missing something in the middle. Maybe we need to improve our reality."