Cash netted for the first time in a league fixture since August last year in Wednesday’s 3-1 win over Brentford and Emery hopes his campaign is now properly up and running.
The 27-year-old has already spent two periods out injured this term, with Emery also preferring to play Ezri Konsa at right-back in certain matches.
But the Villa boss said: "Matty Cash is a very important player for us.
"We always have to be careful with him because he has had some small injuries.
"His qualities are his speed - he is a very fast player who plays with a lot of intensity in each match.
"Now, with the way we play, Cash is one of the key players for us.
"We have tried to add other players to compete with him like Kosta Nedeljkovic and Ezri Konsa has helped us on the right side too, defensively and offensively.
"But the best player we have there to defend and attack on this side is Cash."
Teenager Nedeljkovic, who joined from Red Star Belgrade last summer, could be moved out on loan tomorrow to aid his development.