Garde admitted this was “painful” and was clearly frustrated by Alan Hutton’s “silly” own goal midway through the second half which presented Watford a 2-1 lead.
Garde has Jores Okore back after injury for the first time since the FA Cup final and will soon have Tiago Ilori competing for a spot in defence too.
“I have many players who can play also at the back, not too many in all positions. But some are possibilities for me, I will see.
“It is not always individuals though, it is sometimes collective. But also as individuals, for sure, they have to improve their level.”
Odion Ighalo gave Watford the lead, but Micah Richards levelled the score just before half-time, before Alan Hutton’s gaffe.
Lifelong Villa fan Troy looked to have sealed it, but Jordan Ayew gave Villa hope. But they were unable to find an equaliser in 10 minutes of stoppage time.
Watford boss Quique Sanchez Flores praised his strike force of Ighalo and Deeney.
He said: “It’s amazing the connection they had during the match. They are able to play on the long ball or on the floor. They cope well with whatever way we play.”
Guzan, Hutton, Richards, Clark, Richardson, Veretout, Sanchez, Gana (Gestede 82), Gil (Traore 68), Ayew, Sinclair.
Okore, Bacuna, Westwood, Lescott, Bunn.
Gomes (Arlauskis 67), Nyom, Cathcart, Britos, Ake, Capoue, Watson, Paredes (Anya 67), Deeney, Abdi (Guedioura 81), Ighalo.
Jurado, Ibarbo, Berghuis, Diamanti.