The England stopper has been under intense pressure this season because of a number of high-profile mistakes for both club and country.
The American told talkSPORT: "All goalkeepers go through ups and down.
"Goalkeeping is very much a confidence position. Joe has never struck me as a person who lacks in the confidence department.
"The manager has a decision to make and he's the only one who knows how Joe's performing day in, day out in training. If he feels he's performing well, he'll stick with him. If he feels he needs a rest, he'll put the other fellow in.
"Being dropped can have a positive effect, but that depends how you take being dropped. If you sulk and stop doing your work, it's going to have an adverse effect. If you knuckle down and work even harder and take your chance when you get in again, it can have a positive effect.
"You just never know with these things. That's why it's not as easy as, 'Right, we're going to drop Joe Hart', because you don't want to lose the best Joe Hart, because the best Joe Hart is England's number one."
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