Suddenly, for the San Francisco 49ers, every disaster scenario is on the table. After Sunday’s 20-17 loss to the Seattle Seahawks, bad thoughts hang over the 49ers’ heads like an ominous thundercloud. If they don’t right the ship, the 49ers could miss the playoffs. If that happens, is head coach Kyle Shanahan suddenly on the hot seat? Is Brock Purdy no longer destined to waltz into the $60 Million Club? Might the 49ers squander what looked to be their season to shine, as in, their group image reflected in the Vince Lombardi Trophy?

Deep breath. Plenty of season left, right? But a 5-5 record at this point is no bueno. Let’s discuss the offense. This 49ers team should win every game in which its defense holds the bad guys to 20 points or fewer. The 49ers are supposed to be a big-play team, but on Sunday, they were hunt-and-peckers. They punched like Mike Tyson throwing pillows in his pathetic comeback “fight” Friday. The 49ers could not bust big plays. Way too few chunk plays (10 or more yards). If they were an ice cream flavor, the 49ers would not be Ben & Jerry’s Chunky Monkey, they would be a generic rocky road.

Other than a handful of big plays by bustout wideout Jauan Jennings and a few off-schedule runs by Purdy, there was no there there. (Apologies, Oakland, but Santa Clara’s closer to you than San Francisco.) A team that went into the season with a stunning array of offensive game breakers, with one of football’s recognized offensive brainiacs calling the plays, is suddenly Team Tepid. More For You 49ers’ season on the brink after after a now familiar late-game flop The San Francisco 49ers were angry and bewildered after Sunday’s 20-17 loss to Seattle…

49ers’ Christian McCaffrey fine physically, still searching for running rhythm San Francisco 49ers running back Christian McCaffrey got through his first two games of… The 49ers were short wide receiver Brandon Aiyuk (out for the season) and tight end George Kittle (out for the game), but they still featured Purdy, last season’s near-MVP, running back Christian McCaffrey, big-play Deebo Samuel and explosive running back Jordan Mason. Yet they rolled up just 277 yards in offense against a struggling Seattle team that just lost its best tackler. The 49ers rushed for 228 yards in a win at Seattle on Oct. 10; they gained just 131 on the ground Sunday.

Ricky Pearsall had zero catches. Samuel caught four balls, for 22 yards. Even with McCaffrey unable to bust out any of his signature defensive-slashing moves, Mason got just two carries, for 13 yards. Even the players’ quotes were, uh, off-target. Pearsall, a recent real-life shooting victim, said, “We shot ourselves in the foot a few times.” Ouch. The 49ers rolled into this season as potentially the most explosive offensive team in the league. So many playmakers! That factor was completely missing Sunday.

When asked where the big plays were, Purdy said the Seahawks “just did a good job with our opportunities to go deep. They kept everything in front of them, (it) felt like, from what I can remember. Obviously, I’ve gotta go watch the film.” Obviously, that will be painful. Especially for Shanahan and Purdy. “He obviously took ownership for himself, as well,” Purdy said of Shanahan’s postgame locker-room post mortem speech to the team.

Shanahan has three more seasons on his contract after this one, so he’s not going to get fired, but if he doesn’t turn around this season, that subject will warm the winter on social media and wherever such matters are discussed. Uneasy would lie the head that once again failed to wear the crown. Shanahan’s challenge now is to restore the fear factor that the 49ers brought into the season.

To do that, Purdy must return to the form of, say, the previous Sunday, when he looked like a $70 million quarterback. On Sunday, he could not outduel one of the league’s most pedestrian quarterbacks, journeyman Geno Smith. The 49ers could have iced the game, taking possession with just less than four minutes left and a 17-13 lead. On 2nd-and-11, Purdy threw behind a wide-open Samuel for what could have been the game-icing play. Purdy said he was trying to avoid a linebacker and sailed the ball.

Purdy’s best work was with his feet, gaining 40 yards on five off-schedule runs, including an 11-yard touchdown scamper to end the first quarter and give the 49ers a 7-3 lead.

Problematic, though, is Purdy’s swashbuckling style. He is reluctant to slide, staying up to get a few extra yards. On two sideline scampers, he tight-roped the chalk, rather than stepping out to avoid contact. Courageous, no doubt. Smart? Uh…

As he reviews video, Purdy might want to go to the archives and look at the play in 2018 when Jimmy Garoppolo stayed in-bounds one step too many and got his knee blown out in Kansas City, three games into the season. The 49ers came back in 2019 to reach the Super Bowl. This season is different. This is the 49ers’ window, right now. But they’d better push it open, or watch their fingers.