Garde started the Cup tie with Grealish.
"You saw the game," said Garde. "Jack started and it was his first for quite a long time now, but I haven't seen exactly what I wanted to see from him tonight.
"I know he has played in the part of the game when we were not good collectively, when we were disappointing for the first hour or so. But then we started to play more collectively and simple.
"But it's not only about Jack; I was not happy with the way the team played the first hour. We were the Premier League team but for too long tonight I did not see that."