France international Pogba swapped Juventus for Old Trafford in August for a fee of around £89m, surpassing the previous world-record transfer that saw Gareth Bale depart Spurs in 2013.
Pogba has taken time to truly get going at United following his high-profile move, but Alli has had another season to remember at White Hart Lane after scoring 14 goals in 32 appearances in all competitions.
Redknapp now values Alli at a higher level than Pogba and admits to being shocked at how former side Spurs brought him to North London unchallenged by their top-flight rivals.
"I think he's fantastic. Can you tell me how all those scouts failed to spot him when he was playing for MK Dons every week? How did they end up waiting until Tottenham came in for him?" he is quoted as saying by The Mirror. "It's incredible that no-one took him. What a player, what a signing — what a steal at £5m.
"I think he's worth £100m now – if Pogba's worth £90m, Alli is worth more. He's just 20 years of age, for heaven's sake, and the kid's got everything. He scores goals, makes goals, he can dribble, head it, he's got an edge to him and puts his foot in... I think he's fantastic.
"Didn't he play for MK Dons against Manchester United when they beat them 4-0 in the League Cup? United should have signed him there and then. At least they would have gone home disappointed with the result but they would have had a future star for the club with them on the bus."
Reports emerged earlier this week claiming that Alli will be made the subject of a world-record bid by Manchester City during the summer transfer window.