Although West Bromwich Albion and Stoke City occupy the bottom two positions and Hull City's form has nosedived with one win in 18 league games, Redknapp, whose side are also fighting against the drop, believes they have improved the league.
"A lot of the big clubs like us, Newcastle and Manchester City have all been down there this year," Redknapp said.
"The clubs who came up have given it a fantastic go, they levelled it up. Hull got off to a fantastic start and obviously now they are in the relegation battle.
"Stoke are scrapping for their lives. West Brom play some terrific football so its a tighter league for sure. It's the tightest fight I can remember but we have enough players here who have the stomach for the battle, without a doubt."
West Brom lie four points adrift but only six points separate 11th-placed Manchester City from Stoke, who are 19th.
Redknapp's side, who lost Sunday's League Cup final to Manchester United on penalties, are currently 14th, but have only two points more than 18th-placed Middlesbrough, who visit White Hart Lane on Wednesday.
"The weekend's results, with Middlesbrough beating Liverpool and Blackburn winning at Hull, opened everything up again," Redknapp said.
"We played well on Sunday and it was great to be in the final, but unfortunately we are stuck in a battle at the bottom. We have got 12 games left and I think if we win four games we should be safe."
Four of those matches are against the top four sides with Spurs having to visit Aston Villa, Manchester United and Liverpool, with Chelsea playing at White Hart Lane.
"We haven't lost to a top four team in the league this season," Redknapp said. "We can beat anyone on the day, but it's a tough call on who will go down."
