Redknapp kept Birmingham in the division last season and then oversaw a busy summer of transfer activity, with 14 players brought in to bolster his promotion push.
Despite taking just four points from the first 24 on offer, though, the experienced boss claims that whoever replaces him will inherit a squad capable of a top-six finish.
"Birmingham City going forward will have a much, much better team than what they had last year," he told talkSPORT. "I still think there is every chance they can put a run together and make the playoffs. It is a long season.
"You can go on a run and suddenly you find yourselves on the verge of the playoffs and I think this squad is good enough. This is a great job for someone because it is a good club with great support. They have got a good opportunity.
"I was really excited about it this year. I went in for the last three games of last season, we managed to stay up, and I was really looking forward to this season. I thought I was going to put a team together here that was going up, I really believed I could do it."
Birmingham, who sit 23rd in the Championship table, return to action next weekend with a trip to face Midlands rivals Derby County.