Isaiah Hartenstein leaves Knicks for $87 million deal with Thunder

The Thunder made Isaiah Hartenstein an offer he couldn’t refuse and one the Knicks couldn’t match.

Hartenstein, the Knicks’ beloved center, agreed to a three-year, $87 million contract with the Western Conference’s No. 1 seed last season, according to ESPN.

The Knicks could only offer four years and $72.5 million.

Hartenstein’s representatives worked on the deal overnight as the NBA’s free agency window opened Sunday, according to ESPN, and the Thunder added much-needed size.

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The Knicks will now have to find a backup center in a limited market.

Hartenstein’s contract has an average annual value of $29 million, more than 50 percent more than the $18.1 million his deal with the Knicks would have been.