The Spanish goalkeeper will spend the season on loan with former Anfield manager Rafael Benitez at Napoli with the view to signing a permanent deal next summer.
Rodgers says the move is a clear indication that the Reds are evolving and suggested that he could not afford to pay Reina's wages - in excess of £100,000 a week - for him to sit on the bench after signing Simon Mignolet from Sunderland for £9million.
"This team is evolving. It's my decision," said Rodgers.
"Last year I had to make decisions in pre-season for the financial stability of the club and that's something I've obviously had to do this year as well.
"Financially, it is something we needed to look at. I had a good chat with Pepe the other day and he knows where it's at.
"It reared its head over the last few months and I had to prepare for it by bringing in another goalkeeper anyway.
"Pepe is a good guy and I've got a lot of time for him. He's been a real pillar for me in terms of how I want to operate.
"But he's got a big season ahead because it's a World Cup year and one where, if he wasn't going to be playing, that could severely harm his chances of going to the World Cup. We both understand that."