Villa’s new boss has had just one game in charge – a 2-1 defeat by Stoke last weekend.
Krulak says owner Randy Lerner has already seen enough to be impressed though.
“We showed a lot more spark in that game than we have been doing, that’s for sure,” Krulak, a lifelong friend of Lerner, told me.
“There was more vigour and attacking threat. It was just gutting to let a late goal in and lose that game.
“Randy is a realist and knows we have a fight on our hands. But he is extremely confident that Tim will keep the team up.”
Villa are second bottom of the Premier League, level on points with Burnley and QPR above them.
Lerner watched Sherwood at first hand when he visited Villa’s training ground before attending the Stoke game last week.
“Tim is a positive, hungry young manager and that’s a big reason why he was selected,” added Krulak, 72.
“Randy saw he was hands-on in training and his positive attitude seemed to rub off on the players.
“There was a good atmosphere about the place and all the players seemed to be very focussed.
“Randy has always believed in these players. There is a lot of ability there, even though we might not have seen too much of it lately.
“We’ve got no doubt that things will start to turn around for the club very soon.”
Krulak said he understood why some fans had questioned Sherwood being the only candidate interviewed for the job – but that it was Lerner’s prerogative.
“The fans absolutely have the right to make these kinds of comments,” he said.
“But the difference is that Randy is the man who is there on the spot. He’s doing what he believes is best for the Villa.”
Villa take on Newcastle in the Premier League on Saturday.
* A shorter version of this story appeared in The Sun newspaper.
