This detail about Kyle Shanahan's coaching is almost unfathomable

BOSTON -- Kyle Shanahan's team lost the Super Bowl. Again.

Kyle Shanahan is getting roasted by the internet. Again.

Such is life when you play the biggest game on the biggest stage and come up short. Shanahan now knows that feeling much more than he'd like, as Sunday night's 49ers defeat marked his third time losing a Super Bowl as a coach. He was at the helm of the Falcons' offense that failed to put away the Patriots in Super Bowl LI after taking a 28-3 lead, he was head coach for 49ers team that blew a 10-point fourth-quarter lead in Super Bowl LIV, and he was head coach again on Sunday, when his 49ers blew a 10-0 lead, blew a 16-13 lead, blew a 19-16 lead, and blew a 22-19 lead.

It's not good.

In this particular game, there were multiple reasons for the ridicule to come pouring in. Some came from his decision to call a pass play out of the two-minute warning. Not only did it not work, but it allowed the Chiefs to keep an extra timeout in their pocket for the eventual game-tying drive (which was real close to being a game-winning drive). Had the Niners simply run the ball on third down and then on fourth down if necessary, the win would have been in their grasp.

Another significant point of criticism came from Shanahan's decision to receive the ball in overtime. Under the new rules, both teams are guaranteed a possession, so many believe that kicking the ball to the opponent is the wiser move. There's merit to that belief ... but it's not as rock-solid as some are expressing. If both teams match scores on their opening drives, then sudden death begins. And possessing the ball first under those circumstances would be extremely advantageous. So it's not as if Shanahan's decision was indefensible. Clearly, there's some new strategy at play that coaches will need to bat around in these rare instances of playoff games in overtime.

Yet it's in that scenario that we can find the biggest, most inexplicable, unforgivable gaffe made by Shanahan in this Super Bowl loss:

His players didn't know the rules.

Let's say it again, but louder:

The 49ers didn't know the new playoff overtime rules.

That's not hyperbole. 

"Multiple San Francisco players said after the game that they were not aware that the overtime rules are different in the playoffs than they are in the regular season, and strategy discussions over how to handle the overtime period did not occur as a team," The Ringer's Lindsay Jones reported.

Jones noted that defensive lineman Arik Armstead did not learn of the new overtime rules from his coaching staff; he learned them from the video board that displayed the rules at the start of overtime.

The story continued:

Fullback Kyle Juszczyk said he assumed the 49ers asked to receive when they won the toss because that's what you do in the regular season, when a touchdown wins the game. "I guess that's not the case. I don't really know the strategy," Juszczyk said. 

This is borderline inconceivable. 

While, sure, the players' jobs require them solely to do what's asked of them on a play-to-play basis, there has to be a fundamental understanding of what's at stake on each of those snaps. That's how sports work.

The Chiefs, Jones noted, were well-versed in the new overtime rules, dating back to training camp. Chris Jones said the team "rehearsed" overtime scenarios over the past two weeks.

The Chiefs, not coincidentally, are now Super Bowl champs. Shanahan's 49ers are not.

Shahanan, we assume, knew the rules. But not passing that information onto the players at any point before the game is about as bad of a coaching nugget that's ever come out of a Super Bowl.