Benitez believes his former target joined Manchester City for the money.
He said: “In this market now, money is not the main thing. Everyone at this level earns big money.
“If it’s just for money sometimes you will make mistakes. I was surprised by some decisions this year, like Gareth Barry.
“I won’t say too much but clearly it was 100 per cent for money. The most important thing for me is the passion of the players.”
He added: “Signing a lot of good players is good but no guarantee, so it will be interesting to see.
“It may be more difficult next season now but experience is so important and we have more than in the past.
“Money to sign good players does make it easier but only if you have understanding between the players. That’s crucial.
“The understanding between our players is much better. We’ll have our chances this season.”