The American reacted to the flood of anti-Alex McLeish messages to the club.
Krulak said: "The uproar over McLeish is uncalled for.
"He has proved he can manage in the big leagues - just imagine what he could do if he was with an owner who supported him."
In a message to Villa fans, he said: "You cling to the fact he's seen his lads relegated twice. Well, the first time he was not with the club long enough to make a difference. Secondly, look at the owners he's worked for and support of him monetarily.
"Then look at our owner Randy Lerner and what he provides to his managers.
"Ask Alex Ferguson about the man. We need to do what is right for the club."