The Denver Broncos could be without their All-Pro linebacker to start the 2013 season. Von Miller is facing a four-game suspension for violating the NFL’s drug policy. He is currently appealing the suspension.

The suspension may not be what you think it’s for.

George Atallah, spokesman for the NFL Player’s Association said the union was working with Miller on his appeal. He then went on Twitter and said, “I can also confirm that Von’s case does not involve the Steroids and Related Substances Policy.”

What could it be?

This is not Miller’s first run-in with the NFL’s drug policy. According to Mike Klis of the Denver Post, in 2011 during Miller’s rookie season, the linebacker tested positive for amphetamines and marijuana.

If Miller’s suspension is not PED-related, could it be related to his past use of recreational drugs? It would be an assumption anyone would make about a player who’s already been flagged for previous drug use.

The Denver Broncos are not commenting on Von Miller’s possible upcoming suspension until the appeal process concludes, per team policy.

Don’t expect a specific cause of Miller’s failed drug test. In the past, the NFL has been vague about the exact substance a player used to fail their drug test. The trendy drug many players “say” they’ve failed a drug test for is Adderall, which may or may not be true.

This story is still developing and we are sure to hear more about it when or if the official suspension is handed down.