The midfielder scored his third goal of the season in a 2-1 win over Crystal Palace on Sunday.
It was the Argentinian's sixth goal in his last six appearances at Vicarage Road and Gracia is pleased with his all-round contribution.
"Pereyra has scored many goals, everybody knows he's an important player for us," said Gracia. "I think in this moment he feels confident. He finished very well his chances to score, but I think he's not only a player who's scoring goals.
"He's working with a good balance with the rest of the team, he's showing a very good attitude when we lose the ball and pressing like the rest of the players.
"In this moment, for me, the most important (factor) is the attitude of the team, not only one player, but everybody knows he's playing well."