While his team have lost just twice in the last nine matches, five draws and only two wins have seen them drop to within two points of the bottom three.
Of greater concern is their status as the top-flight's joint-lowest goalscorers (10 in 13 fixtures) compounded by their current run of four games without a goal.
"Sometimes me, my staff and the players haven't delivered as well as we could do," he said.
"But we work tirelessly. This is the most work I've done in all my years in management, at this club, without a shadow of a doubt.