Redknapp has transformed Spurs' fortunes since taking charge two sand a half years ago, leading them from the bottom of the table to the quarter-finals of the Champions League.
The bubble has burst somewhat in the last two months, with one win in 10 games seeing them exit Europe and drop four points behind Manchester City in the race for fourth place in the league.
Their five remaining games include today's trip to Stamford Bridge - where they have not won in the Premier League era - and away matches at Liverpool and City.
So unless their form changes dramatically, they look set to miss out on a second successive season in the Champions League, something that will make any attempt to bolster their squad all the more difficult.
Ancelotti said: "They played the quarter-final of the Champions League.
"If you are not able to do this the next year, it will be more difficult to manage and to attract the players to your team.
"When you have the smell to play the Champions League, you would like to play every time the Champions League."
Despite his side's recent slump, Redknapp remains the hot favourite to succeed Fabio Capello as England manager and his bid has been given the thumbs up by Ancelotti.
"He has the ability, the skill, the experience to manage the England team in the future," the Italian said.
"I saw his team play. They are playing with good organisation.
"As a manager, he has a very good relationship with the players."
That relationship is crucial, according to Ancelotti, who knows the importance of managing all the egos within a squad.
He will have to do that when again he names his team for this afternoon's game, having decided whether to pair Fernando Torres and Didier Drogba in attack or leave one of them on the bench.
"This is psychological," Ancelotti said.
"I think that when you speak, you have to put in their mind that the most important thing is the team.
"The best thing for a player is, obviously, to use the individual abilities of the player for the team.
"You can fight against the ego for this reason.
"The difference between a good player and a top player is this: a top player is a player who is able to give his ability to support the play of the team."