The Hoops won 4-1 in Indiana. Matt O'Riley, Kyogo Furuhashi, Luis Palma and Mickey Johnston struck for Celtic. Christopher Nkunku scored a late Chelsea consolation from the spot.
Maresca later said: "As we said, the result is always important. For us, we need to analyse the game in general. I think on the ball, the team were 10 times better than in the game against Wrexham and that is important because we can see the amount of chances we created first-half and second-half.
"And off the ball, for sure, we can improve things and you can see sometimes we confuse when we need to play short, a little bit longer. It's part of the process.
"Yeah because they were marking us man-to-man; the idea was to try and find some solution in behind but it is something we prepared on the tactical board and didn't try in the training session. The reason why is because we are trying so many things and we don't have enough time to try everything. We started just 15 or 20 days ago.
"But when we started the game, after five minutes, we already had two or three chances. And then in the second-half, until the third goal, the team was very good and created chances. We didn't concede any shots until the 75th minute and then conceded the goal and it was more difficult.
"What was important to realise was the difference between us and them in terms of physical condition. You can see they played already three or four games and they start the season soon. For us, you can see we struggled a bit physically."
Maresca also said: "For sure, we need many things to improve off the ball. One of the things we did bad today was when the ball was not under pressure, to maintain the high-line. When the ball is not under pressure, you need to drop.
"We still confuse some things on and off the ball. For me, it's normal in this moment. We are trying to do something new. But for sure, game after game, training after training, we are going to be ready."