The Argentine has netted three goals and helped the 'Hornets' achieve three wins for their first three matches, and will have the chance to add to his tally against Reading in Wednesday's Carabao Cup fixture.
However, it is his attitude rather than his goalscoring that has impressed Gracia.
"He is an important player for us. I think in this moment he feels confident and he finishes his chances to score very well.
"He is working with a good balance with the rest of the team. He's showing a good attitude when we lose the ball, pressing high.
"Most important at the moment is the attitude of the team, but everybody knows he is playing well."
Watford will host Tottenham in the Premier League on Sunday.