When Eric Reid arrived back at his locker after the Panthers lost their sixth-straight game on Monday night, a familiar sight greeted him. Once again, the NFL selected Reid to be randomly drug tested.

According to Reid, who is involved in an ongoing collusion grievance against the NFL, this is the seventh time he's been drug tested since he joined the Panthers 11 weeks ago.

Speaking with reporters after the game, Reid challenged the notion that he's being randomly selected.

"I've been here 11 weeks, I've been drug tested seven times," he said. "That has to be statistically impossible. I'm not a mathematician, but there's no way that's random."

Reid, who protested social injustice with Colin Kaepernick in San Francisco and has continued to do so this season, signed with the Panthers at the end of September after going unsigned during free agency over the summer even though he was one of the best safeties available on the open market after a career-season with the 49ersHe filed a collusion grievance against the NFL in May. 

When asked if the drug tests would become part of his collusion grievance, Reid replied "Duly noted."

It wasn't just Reid who found the frequency of the drug tests odd. So did former and current NFL players. 

So, what are the odds that one player could be selected seven times for drug testing by the NFL in an 11-week window? Yahoo Sports' Jack Baer, who noted that one of those seven drug tests came when he initially joined the Panthers as part of his physical, did the math:

Using a cumulative binomial probability calculator, those numbers work out to a 0.17 percent chance of Reid getting randomly selected at least six times in 11 chances, according to the NFL's rules. That's a 1-in-588 chance. Reid would have a better chance at correctly guessing a coin flip nine times in a row.

Since joining the Panthers, Reid has racked up 64 combined tackles, four broken up passes, one sack, and one interception. During Monday night's game, Reid wore cleats that honored the history of protests.