Redfearn picked up 10 points from a possible twelve in the league during his spell as caretaker manager, but Massimo Cellino opted to install Milanic as the club's boss instead.
The former Sturm Graz coach arrived at Elland Road on Tuesday and lost 2-0 to Brentford in his first game in charge - a result which would have been less likely had Redfearn still been at the helm, according to Claridge.
"He had such a dramatic effect," Claridge told BBC Sport. "You do get the feeling, certainly from a Leeds perspective, that sometimes the answer is right under your nose and they've overlooked it.
"You do think maybe that was an opportunity missed with Neil Redfearn."
Leeds are currently 13th in the Championship following four wins, four losses and a draw from their opening nine games.