But, it didn't take long for Walker to find employment elsewhere ... inking a deal to reunite with his old coach, Matt Rhule in Charlotte.
Walker played under Rhule at Temple from 2013-16 ... and broke a bunch of school records in the process.
FYI -- Walker was a straight-up beast on the field for the Roughnecks ... passing for 1,338 yards and 15 touchdowns. Walker had a brief stint with the Colts after college but never made it off the practice squad.
It's not the first time a breakout XFL star has made their way to the NFL ... with Rod Smart AKA "He Hate Me" becoming a household name in the early 2000s.