Keane worked under Paul Lambert who was fired earlier this year, quitting prior to that to concentrate on his role with the Republic of Ireland team.
Villa are a team transformed under Tim Sherwood, with no player embodying that more so than Benteke, who has scored 11 of his 12 Premier League goals this season under his the manager.
Keane said he was underwhelmed by the Belgian forward during his time at the club. He said: "“I thought he’d give them a lift when he came back from injury . . . but I wasn’t thinking ‘The Messiah’s back’.
“He isn’t the type of personality that will get people together.”
The same accusation could be levelled at the controversial Keane, whose man management at his previous clubs Sunderland and Ipswich Town left much to be desired.
He even admitted as such in his autobiography, reported by ITV: "I don't think I'm a bad manager, but at Ipswich I managed badly. I spoke to some people like something on the bottom of my shoe."
The opposite is true of Tim Sherwood whose motivation and keenness to talk positively to and about his players have helped him get the best out of them, especially Benteke.
Keane added that he was disappointed with Sherwood, because he was spotted in the crowd at Villa Park watching on while Paul Lambert was still manager.
He said: "I went to watch Villa against Bournemouth in the FA Cup a few weeks before Paul was sacked and Tim Sherwood was sitting behind me. I just thought, All right . . . ’
“I think some men go to matches if they think there’s a job there for him."
Sherwood was certainly needed at Villa, who had dropped into the relegation zone when Lambert was fired.
The former Tottenham head coach has steadied the ship, and while they are not safe yet, they are on track to survive, and remarkably are into the FA Cup final, where they play Arsenal at the end of the month.