Patriots fans would be forgiven for laughing at the notion of Tom Brady and Jimmy Garoppolo trading places this offseason.

However, the hypothetical swap reportedly is no laughing matter.

NBC Sports Boston’s Tom E. Curran on Tuesday reported the San Francisco 49ers are “closing hard on the outside” of the Brady sweepstakes. The news, which Curran delivered during an appearance on Sirius XM’s “Mad Dog Sports Radio,” arrived amid chatter that Brady could be interested in San Francisco and that the Patriots would welcome a reunion with Garoppolo, whom they traded in 2017. Much of the speculation initially came across as just that, but Curran — one of the more tied-in reporters covering the Patriots — added a level of validity to rumor-mongering.

That brings us to the Boston Herald’s Karen Guregian, a similarly in-the-know reporter covering the Patriots.

Check out this bit from her column published Tuesday night:

“Tom Brady to the 49ers. Jimmy Garoppolo back to the Patriots. Talk about a whopper.

“There’s been growing speculation this fantasy scenario could happen, with the buzz hitting a fever pitch on Tuesday thanks to all types of reporting and conjecture from multiple outlets.

” … What do my sources say? Curran “might be onto something.”

Now, it’s not like the Patriots suddenly are all-in on parting with Brady.

From Guregian:

“That’s not to say the Patriots are out of the mix. They are in consideration, provided Bill Belichick finally reaches out to Brady about the nitty gritty of a new contract and his plans for the offense going forward. Ditto for the Titans, who are still in the picture, as well. Playing for (head coach Mike) Vrabel is certainly a draw for Brady.”

Of all the rumors surrounding Brady, the one involving Garoppolo certainly is the juiciest. And, as hard as it is to envision the 49ers moving on from a quarterback who just took them to the Super Bowl (the Niners have publicly backed Garoppolo since losing to the Kansas City Chiefs), it appears the rumors at least have some legs.

Reminder: Brady is scheduled to become a free agent on March 18.

Is Tom Brady-to-49ers a realistic option? >>

Thumbnail photo via Kevin Jairaj/USA TODAY Sports Images