Noni Madueke hit a hat-trick as Chelsea won 2-6 on Sunday. Nicolas Jackson, Cole Palmer and Joao Felix also struck for the visitors.
Maresca said, "In the second half we changed something and it was better. I thought the intention in the first half was good but we lost four or five easy balls from set-pieces and counter attacks.
"The second half was completely different and we didn't lose any balls and were in control of the game. The tactical plan in the second half was the same but we were a bit more accurate in the second half and didn't give away any easy balls."
On whether Chelsea will attack like this every week, the Italian continued: "That is the intention but there are teams there that want the same so it's not easy. In the first 10 minutes we created two or three chances and scored a goal and then we started to lose the ball, but overall a good performance. Absolutely there always things we can improve on. We can learn many things."
On Madueke, he added: "In the first 10 minutes he had two chances and overall he was very good. The only thing I didn't like from Noni is the free-kick he gave away before half-time and we can avoid that. especially against a team who are good from set-pieces."