Tampa Bay Rays outfielder Kevin Kiermaier blasted a ground-rule double in the top of the 13th during Sunday's 6-4 extra-innings loss to the Boston Red Sox, appearing for a moment to give the Rays a 5-4 lead.

But umpires ruled that Yandy Diaz, who clearly would have scored had the ball not bounced over the fence and gone out of play, had to go back to third base, taking a run off the board for the Rays.

"I'm just in awe right now," Kiermaier told reporters after the game. "That's the ruling, the umpires explained it to me. So I can't go against that. The rules are what they are. But man, that's just, that's a heartbreaker."

ESPN's Jeff Passan offered more context on the controversial ruling:

"I saw the replay, there was nothing intentional about it," Rays manager Kevin Cash told reporters, explaining why he didn't challenge the call. "That's just the rules. It's the way it goes, it was very unfortunate for us. I thought it was pretty obvious that Yandy was going to come around to score, but it didn't go our way."

Of course, that opens up an entirely different conversation about whether that rule makes any logical sense at all:

With instant replay now available to umpires, it wouldn't be surprising to see the rule changed, given that the precise positioning of baserunners can be pinpointed at the time the ball bounces over the fence. The old rule made sense without the ability to consult video. But replays showed that Diaz was clearly past second base, nearly to third, and the two bases he should have been awarded with a more logical rule in place would have led to him scoring.

Granted, it may have been something of a moot point, given that Christian Vazquez hit a two-run dinger in the bottom of the inning to walk it off.

But who knows how the game might have changed if the Rays went into the bottom of the 13th with a one-run lead instead of the contest remaining tied?

Regardless, the Rays can't change the outcome and now face an elimination game in Boston on Monday night at 7:07 p.m. ET, down 2-1 in the series.

"We have to put on our big-boy pants," Kiermaier told reporters about the win-or-go-home game.

And maybe have baseball's most obscure rules go their way, too.