Keown, now a pundit on Match of the Day 2, told the Evening Standard: "Keane remains a top-class forward but it can be no coincidence that since his departure, the Reds have found their best form - with Steven Gerrard and Fernando Torres fit and at the fulcrum of the revival.
"No matter what Keane's contribution was in any match following his £ 20.3million move from Tottenham, he was always the talking point. Rafa Benitez had to field endless questions about the Irishman and it was draining for the manager and player, who both deserved better.
"Keane was bought [for £20.3million] to play off Torres, but Gerrard was consequently pushed back into midfield which only stunted the effectiveness of their captain and contributed to a lack of fluidity. But Benitez's best team is now obvious.
"Rafa's 4-2-3-1, with Gerrard pushed further forward behind Torres, is now a devastating system that maximises everything from the players he has at his disposal - as was demonstrated by the England player's superb hat-trick yesterday against Aston Villa."