He told AVTV: "Brad has been a terrific goalkeeper for a number of years. That was a significant reason for signing him.
"His performances have been fantastic for many years.
"There have been one or two games for us where he felt he could have done better. He hasn't been completely happy with a few of the goals he has conceded and it's great he is looking at those sorts of things.
"He is a professional still thinking greatly about his game. He has come to Villa and he really wants to prove himself again here.
"That is very encouraging and it's great to have him. It's fantastic to have Brad Guzan pushing him too. I think he has real competition.
"When we went to Prague, I thought Brad's performance was terrific. I think that sort of quality competition keeps good players on their toes."