The bottom line is,
Kevin Durant is already making the maximum,
Russell Westbrook's maximum extension kicks in next season, and when
James Harden and
Serge Ibaka both reach free agency a year from now in 2013, the Thunder will not be able to retain both of them unless they intend to venture well into luxury tax territory. And because Durant and Westbrook won't be going anywhere any time soon, large contracts for Harden and Ibaka would likely mean paying the tax for the duration of those contracts -- which means the extra harsh "repeat offender" tax.