Jeffrey Becker-USA TODAY Sports

The NFL and NFL Players Association have begun an inquiry into the on-field machinations of New England Patriots wide receiver DeVante Parker's head injury sustained in Monday night's game, ESPN and NFL Network reported.

Specifically, the league and union are reviewing why the game wasn't stopped despite Parker wobbling after a hard hit in the first quarter. Instead, it was Parker's teammate Nelson Agholor who beckoned game officials to stop play and get Parker off the field.

Parker was subsequently removed from the game when the Arizona Cardinals challenged his catch on the play in question. He was then ruled out for the rest of the game.

Parker on Tuesday thanked Agholor for being "aware of the situation" while calling out the NFL -- with profanity -- on his Instagram page.

It was reminiscent of Miami quarterback Tua Tagovailoa being allowed to return to a Week 3 game after he was wobbly following a hard hit to the turf. That incident prompted a change to the concussion protocol; ataxia was added to the list of no-go symptoms. Ataxia is defined as "abnormality of balance/stability, motor coordination or dysfunctional speech caused by a neurological issue."

Parker caught a 10-yard pass at the 4:19 mark of the first quarter and went to the ground hard on a tackle by the Cardinals' Antonio Hamilton. Parker was slow and wobbly to get up, but play wasn't initially halted by spotters.

Parker, 29, has 25 catches for 460 yards and a touchdown in 12 games (10 starts) this season, his first in New England.

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