Nobody knows how it happened or when it happened. But it happened, and it has left the Cleveland Browns reeling.

Quarterback Deshaun Watson, who was finally healthy again, led his team to a dramatic 33-31 victory over the Baltimore Ravens Sunday in Baltimore. Three days later, Watson was diagnosed with a fracture in his throwing shoulder that will require season-ending surgery.

“I felt something towards the end of the first quarter,” Watson said. “I kind of recognized something was wrong but during the midst of the game and everything going on, I was just trying to lock in on the next play.”

Watson underwent tests on Monday, “and that’s when I found out from the doctors that it was something worse than what we thought it was.”

Worse for Watson personally, and devastating for the Browns organizationally. Winners of four of its last five games, Cleveland, with a record of 6-3, seemed to be gaining momentum in its push for a spot in the playoffs, or perhaps even its first division championship in 34 years.

Watson’s injury changes all that, despite Browns executive vice-president and general manager Andrew Berry’s pronouncement that, due to all the adversity the team has faced this season, including losing Watson and running back Nick Chubb to season-ending injuries, Cleveland’s players, coaches, and staff “have grown Teflon skin and cast-iron stomachs.”

The Browns, and their fans were still celebrating the team’s win over the Ravens, when the bad news was delivered on Wednesday.

“We are very disappointed and devastated for Deshaun, especially given all that he has battled and gone through medically this season, especially in light of how well he’s played since his most recent injury,” said Berry.

In addition to his fractured shoulder, Watson also suffered a severe ankle injury and left the locker room Sunday wearing a walking boot.

“I’m incredibly disappointed for the kid,” said Cleveland coach Kevin Stefanski. “He battled like crazy to get back out there, then for what he did (in Sunday’s game) was even more remarkable.” In leading the Browns to a last-second victory in Baltimore, Watson completed every one of his 14 second half passes, while playing with a fractured shoulder, and ankle sprain.