Brown and the Chiefs weren't able to agree on a long-term extension ahead of Friday's deadline, Tom Pelissero of NFL Network reports.
Per Pelissero, Kansas City offered Brown the highest signing bonus and average salary per year allowed on a six-year deal, and Ian Rapoport of NFL Network reports that the deal would've been more than Trent Williams' current contract (six years, $138 million). However, Rapoport relays the deal fell through due to security and structuring issues. The 26-year-old has yet to sign the $16.7 million franchise tender, but it remains unclear if Brown has any intentions of skipping training camp.