With quarterback Jay Cutler missing the trip as he recovers from a concussion, backup Jason Campbell filled in ineffectively, and suffered five sacks behind poor protection in addition to throwing two interceptions to finish with a passer rating of 52.7.
The defense couldn't bail out the offense, either.
Although the defense had saved the offense seemingly countless times already this season, the turnover finally dried up for Chicago's takeaway-happy unit. The loss marked the first time all season the Bears defense failed to force a turnover.
What it means: The team's 7-1 start certainly brought optimism about its prospects for the season, but the Bears gave up their NFC North lead with Monday's loss and now sit behind the Green Bay Packers with upcoming matchups against Minnesota and Seattle, both 6-4. Having lost now to all three opponents they've faced with winning records (Packers, Texans and 49ers), Monday night's slaughter might have provided somewhat of a reality check for the Bears.
It's apparent they're probably not be the contender they thought they were just weeks ago. But at the same time, the Bears can certainly develop into that. The fact is that the teams that advance deep into the playoffs typically start peaking near the end of November and into December.
So the harsh dose of reality force fed to the Bears by the 49ers on Monday can either derail the club's season or serve as the catalyst it needs moving into crunch time. Only the Bears can determine how they'll respond from this.
OL woes: Perhaps Campbell should have pulled a Cutler and barked at the offensive line, bumped some of them or something to motivate the unit, considering the way it performed in giving up five sacks against the 49ers. As usual, offensive tackles J'Marcus Webb and Gabe Carimi served as the most egregious offenders up front. The former seemed confused by San Francisco's twists and the latter once fell flat on his behind when Aldon Smith bull rushed right through him on the way to a sack.
The loss to the Texans last week marked the first time the offensive line finished a game without giving up a sack. The unit has now given up 33 sacks with six games remaining, after allowing 49 in 2011.
Timely signing: It certainly appeared to be the case when Campbell took a hard shot from Ahmad Brooks that left him on the turf momentarily writhing in pain. Largely because of shoddy protection along the offensive line, Campbell suffered four sacks and appeared to be on track to be replaced in the lineup by veteran Josh McCown, who was just signed on Tuesday.
Because there was a penalty on the play, Campbell was able to recover on the sideline and re-enter the game. But the Bears came extremely close to needing to play McCown.
Marshall smothered: Prior to the matchup with the 49ers, none of Chicago's opponents fully committed to shutting down receiver Brandon Marshall. The 49ers did, however, and the tactic worked so well it eliminated a huge chunk of the Bears' passing game by taking out Marshall. Defended by double teams and coverage rolled to him most of the night, Marshall didn't make his first catch until the 10:47 mark of the third quarter.
Marshall hauled in a 13-yard touchdown for his second reception of the night, which also gave Chicago its first points of the night with 3:43 remaining in the third quarter. But by then, San Francisco had already jumped out to a 27-0 lead.
Marshall came into the game averaging 7.4 receptions and 100.4 yards, and left having caught two passes for 21 yards and a TD.
Shoddy safety play: Inconsistency at the safety position seemed to be a hallmark of Chicago defense in recent years, before the team appeared to correct the problem with solid play through the first nine games from Chris Conte and Major Wright. That didn't last, however, as San Francisco exploited Wright and Conte on Monday night by threatening them for most of the night with tight end Vernon Davis, who caught six passes for 83 yards and a TD.
On several occasions, Davis broke free in Chicago's secondary, running wide open with either Conte or Wright chasing only to be overthrown or missed by Kaepernick.
Dating back to last season Conte and Wright had started 15 games together coming into Monday night, holding opposing quarterback's to a passer rating of 63.7 with the duo combining for eight interceptions over that span.
Kaepernick finished with 243 yards through the air and a passer rating of 133.1 and tossed a pair of TDs.
What's next: The Bears take Tuesday off, before returning to practice on Wednesday in preparation for Sunday's game at Soldier Field against the Minnesota Vikings. Focus is key coming off a loss like this with a short week to prepare.