Last week came word that the NFL had suspended New England Patriots receiver Julian Edelman for the first four games of the regular season for violating the league’s policy on performance-enhancing substances.

And while Edelman said on Instagram that he didn’t know what happened to get the failed test, a Monday report leaves all of us wondering what happened.

‘Substance wasn’t immediately recognizable’

New England Patriots wide receiver Julian Edelman took part in the team’s minicamp last week. (AP) More

In his weekly catch-all column on The MMQB, Albert Breer writes that he was told “Edelman’s result was triggered by a substance that wasn’t immediately recognizable, and there are scientists analyzing it.”

Breer further writes that the test was taken a couple of months ago, during the offseason, which he surmises means it isn’t for a stimulant.

So what is it?

You have to think that the NFL and whatever testing service it uses know of hundreds of different substances, ones that would – and wouldn’t – trigger a positive test. So it seems really strange that Edelman reportedly tested positive for something that wasn’t recognized.

In the immediate aftermath of news of the suspension, there were some who wondered if Edelman’s working with Alex Guerrero, Tom Brady’s longtime “body coach” and friend, had anything to do with the failed test.

Guerrero has a history of promoting nutritional supplements that he dubiously claims can do things like cure concussions and help terminally ill individuals, and he’s been investigated by the Federal Trade Commission.

Guerrero defended himself, and released a statement; after saying the news of Edelman’s suspension was disappointing, he added, “Elite athletes sometimes work with multiple coaches and health professionals as part of their training.

“Here at our facility, we take a natural, holistic, appropriate and, above all, legal approach to training and recovery for all of our clients. And anyone who would suggest otherwise is irresponsible, and just plain wrong.”

Did NFL overreact?

There’s one other question: if the substance is unrecognizable, as Breer was told, why did the NFL suspend Edelman for it? Are they assuming guilt first, and will reverse course later if it’s not found to be a performance-enhancer?

Edelman, who missed all of 2017 after suffering a torn ACL in the Patriots’ third preseason game, has appealed the suspension. The 32-year-old been taking part in the team’s offseason program, including last week’s mandatory minicamp.

More from Yahoo Sports:

• Braves star robbed of more than $100K while pitching

• Former Patriots lineman Jones dies at 39

• Clemens’ homer-mashing kid is taunting everyone

• Jeff Passan: Is one genius’ dramatic proposal the way to fix MLB?

