The Englishman has joined on a permanent transfer from Arsenal, seeking more playing time.
While he has not enjoyed the best of games in terms of goals conceded, Martin is happy with his goalkeeping.
“He’s a top goalkeeper," Martin said. "He’s played three games and I don’t know how he’s conceded three goals.
“It’s not fair on him really. The stuff he does with the ball at his feet, the decisions he makes, help us as a group and as a team.
“He’s a top goalkeeper and he’s showing that. I’ve only watched the equalizer once and that was enough because it made me feel sick."