Heaton suffered a cruciate knee ligament injury against his former club on New Year's Day in what was a huge blow to Villa and Smith.
“He's been there, seen it and done it. Unfortunately he got injured on New Year's Day and it put him out for the season. He's one who adapted straight away but there's others.
“Douglas Luiz is playing an awful lot of games. He was playing La Liga last year so he's found it a little bit different."