There’s something about losing a Super Bowl to the Kansas City Chiefs. Not only is it devastating in the moment for the San Francisco 49ers, but there are lingering, negative effects that wreck the ensuing season as well.

At the end of the 2019 season the 49ers held a 20-10 lead midway through the fourth quarter of Super Bowl LIV before surrendering a bewildering 21 points down the stretch of a stinging loss. And just 10 months ago in Super Bowl LVIII, the 49ers had leads in the fourth quarter and overtime only to watch the Chiefs score with :03 remaining in both periods of a heartbreaking 25-22 loss.

The residual is real. And real bad.

The 2020 season was a nightmare because of a combination of injuries and COVID. Stars Jimmy Garoppolo, George Kittle, Deebo Samuel, Nick Bosa and Richard Sherman all missed significant playing time, and the Niners wound up with an NFL-leading 18 players on injured reserve. Because of the pandemic and the closures in Santa Clara County, they were forced to play their final three “home” games in Arizona.

Unfortunately, they’re experiencing another horrendous post-Chiefs hangover this season. After entering as the betting favorite to win the Super Bowl and throttling the New York Jets in the opener, things have steadily fallen apart.

Injuries to Christian McCaffrey and backups Elijah Mitchell and Jordan Mason have deteriorated the running game. Receiver Brandon Aiyuk sat out training camp in a contract dispute and has been a non-factor with only 25 catches and no touchdowns. Samuel, who has been injured off an on, dropped a key pass against the Los Angeles Rams in Thursday night’s loss and has seen his performance significantly dip. He has two touchdowns, compared to 12 a year ago.

The Niners’ two-year reign in the NFC West is over because of key home losses to divisional foes at Levi’s Stadium. They coughed up a 23-10 halftime lead over the Arizona Cardinals in October. They let Geno Smith scramble in for a late touchdown in a loss to the Seattle Seahawks. And on Thursday their offense couldn’t get into the end zone against a Rams’ defense that four days earlier allowed 42 points to the Buffalo Bills.

Four of the last five years the Niners have made it to at least the NFC Championship Game. But at 6-8 and with linebacker De’Vondre Campbell symbolically quitting, the Kansas City curse is as strong as ever.