West Ham went ahead thanks to an early error from Estevao before Chelsea overran the hosts to win 5-1 at London stadium.
“Today he showed that he is very mature,” Cucurella told reporters. “He is very young. In theory, he started on the bench. Then in five minutes he needed to get ready.
“He needs to continue to learn and listen to tactics and everything. He had an amazing game. He had the opportunity to score at the end, but he has a lot of quality. He can improve a lot, and hopefully he can continue in this way.
“In the last game at home (to Crystal Palace), we created a lot of chances but were not very accurate. Today we scored five goals. Five different players scored, so I think this shows that we are very ambitious and have a lot of quality.”