Even though they have England internationals Phil Jagielka and Leighton Baines in the backline they have been breached too often for the American's liking.
Howard said: "I think eight clean sheets is a low return and is an under-achievement for the group we have defensively.
"It's hard to put your finger on it. We have been slightly inconsistent and there have been a few individual errors and we've been punished for them.
"We've never been blown away in games this season but the little things make the difference."
Source: PA
Source: PA