Both players had massive contracts, with Westbrook owed more than $38 million next season. His contract is a massive 5-year, $207 million deal, and Westbrook has reportedly moved more of his money to future years to make the trade more palatable for Houston.
Via Marc Stein of the New York Times:
We don’t know how much money was moved around and to which years, but Westbrook is reportedly getting the same amount of money over the course of his contract. He’s not giving up any dollars on paper, although because of the way the time value of money works, you could argue semantics that Westbrook is making some kind of sacrifice here by getting less up front.
All that aside, it’s clear that Westbrook wants to be with James Harden in Houston so that he can try and win an NBA title before his time in the league is done. The Thunder aren’t going anywhere for a little while, and the massive haul of picks they received in exchange for Paul George will put them into contention sometime in the future.
Right now, it makes sense for Westbrook to be in Houston and apparently that means restructuring some items in his contract.