just turned a devastating playoff loss into a really cool moment ... making a surprise visit to the 2nd grade girl who sent him a letter to cheer him up after losing to the Saints.
ICYMI -- 8-year-old Abigail Johnson sent an adorable letter to the Philly Eagles star after watching him let a crucial catch go through his hands, which turned into a game-ending interception.
The letter quickly went viral ... and Alshon eventually got a hold of the encouraging words.
