Pochettino said: "It's difficult because we are talking after nearly one season in the same way, but it's impossible to see Saturday at Wembey a fantastic performance, competing really well against one of the best teams in the world like Manchester City, and then today.
"You can lose games against a team like Arsenal that is fighting for the Premier League, but it is the way we compete, three days ago and then today. We needed to make changes to the starting line-up for different reasons, but that is the inconsistency we have been showing all season.
"Three days ago it was a fantastic game, great performance and we deserved to go to the final. Today you can use any words to describe our performance, it wasn't good."
He continued: "It's true we did not compete. I cannot blame the players, as a team we are showing this inconsistency. That is why we are where we are, because we are capable of having an amazing performance, and three days later to be at the other extreme.
"When we have bad days, we are so bad. When we are good, we are capable of everything. But it's another thing that we need to be aware that we need to improve for the future.
"We cannot blame the players, I'm not going to blame the players. The circumstances are bigger than the performance of the players. We cannot blame young guys who came here and after suffering some circumstances, come here to fight against a team preparing to win the Premier League.
"We cannot be unfair with our players. It is true we are disappointed with our performance, but I am not going to say something which is unfair to describe our team, our players, our squad."