Lampard said the forward needed time to adapt to the Premier League, but Marsch believes Pulisic was being unfairly treated by the Chelsea boss.
"The perception in Europe, mostly, is that the American player is willing to run, willing to fight, has good mentality, but technically they're not very gifted and tactically they're not very aware and their experiences aren't very big," he told Extratime Radio.
"But we're seeing that change. We're seeing more and more of these players develop themselves.
"Even Frank Lampard, when I spoke to him in preseason a year ago now, I was talking to him about having Christian Pulisic, and he was kind of like: 'Yeah, he's got a lot to learn, so we'll see how he does.' I said to him: 'Listen, he was at Dortmund, and they had a high level of tactical thinking, of playing, and he was very successful.'
"He was considered one of the best young players in Germany, and that's in a group of players with Timo Werner, Kai Havertz, Joshua Kimmich, these kinds of players. He was in a group with those players, and it's not just because he was talented but it was because he understood the tactics and understood how to fit in the game and he was developing a real astute way of how to play.
"I could see right away that Frank Lampard's idea of Christian Pulisic was shaped a lot by the fact that he was American and not that his football education came a lot from what has happened in Germany. Since then, I think Lampard has learned that Pulisic is a lot better than he gave him credit for.
Pulisic went on to enjoy an impressive debut campaign at Stamford Bridge, contributing 11 goals and 10 assists in all competitions. He was also nominated for the Premier League's Young Player of the Year award.