"What is Jimmy Garoppolo doing?"

That was our initial reaction upon seeing the play live. With six minutes to go in the fourth quarter and the 49ers trailing, 37-28, Garoppolo was facing a 3rd-and-goal from the Chiefs' 20-yard line. He was flushed from the pocket, found himself running down the sidelines and instead of stepping out of bounds before being walloped by Chiefs safety Steve Nelson well short of the end zone, the 49ers' quarterback cut back inside to gain, at most, another few yards.

In the split second before Garoppolo was blasted by Nelson, his knee left knee buckled, leaving him on the turf in obvious pain.

The 49ers fear that Garoppolo, who signed a five-year, $137.5 million deal in the offseason, tore his ACL and that his 2018 season is now over.

Meanwhile, Chiefs pass rusher Justin Houston has some thoughts on Garoppolo's decision making.

"That was his fault," Houston said of Garoppolo trying to gain a meaningless extra yard or two, via PFT. "I pray he's not hurt, nothing serious, but as a quarterback you should step out of bounds. It was only an inch. That inch wouldn't have made a difference. You got the yardage you need, you step out of bounds. You got to be smart."

How big is the loss of Garoppolo to the 49ers? The team was 1-11 when he took over the starting job last season and promptly reeled off five straight wins. And while he wasn't as consistent to begin the 2018 season, San Francisco's expected win total drops from 7.7 games to 4.8 games with replacement C.J. Beathard, according to SportsLine's Stephen Oh.

So instead of a possible playoff push for the first time since 2013, when Colin Kaepernick took San Francisco to the NFC Championship Game, it's more likely that this team is looking at again picking high in the draft. 

Three weeks ago the 49ers lost running back Jerick McKinnon, signed in the offseason to four-year, $30 million deal, when he tore his ACL.