The San Francisco 49ers found a way to win yet again despite having more holes on their current roster than a Star Wars plot. 

Kyle Shanahan's squad captured a last-second 34-31 victory Saturday over the rival Los Angeles Rams to give it the inside track for the NFC's No. 1 playoff seed despite suffering two losses over the previous three weeks.

San Francisco's last four contests have all been hotly contested. A final play with five seconds or less on the clock decided each game, which can be emotionally and mentally draining. 

The reason behind such competitive performances is simple: Due to injuries, adjustments by opponents and inconsistent performances, the 49ers aren't the same dominant team that they were earlier this season.

The offensive line is in tatters. Quarterback Jimmy Garoppolo looks great one moment and then struggles for stretches. The defensive line hasn't been nearly as effective. And the secondary can be exposed. 

All of these factors are major concerns as the postseason looms. 

The 49ers won six of their first seven games by more than one score. However, they've repeated that feat only twice in their last eight contests. They sport a 5-3 record during that span. 

As per usual, everything starts with the quarterback.

It's unfair to say Garoppolo isn't playing well. But there are points when he doesn't do much to spark San Francisco's offense. The ground game and pivotal play design are often enough to open up things for the 49ers.

To Garoppolo's credit, he's posted big performances this season against the New Orleans Saints and Arizona Cardinals. But his pocket awareness and overall efficiency lagged against the Rams on Saturday.

Fortunately for the 49ers, Garoppolo continues to make plays when necessary. His lone touchdown pass came when he avoided pressure in the pocket, scrambled to his right and found tight end George Kittle for a seven-yard score. That was far from his most impressive throw of the night, though. 

San Francisco faced a pair of 3rd-and-16s during its final drive. First, Garoppolo drove the ball between double coverage to Kendrick Bourne. Three plays later, he connected with wide receiver Emmanuel Sanders for a 46-yard gain to place the 49ers into field-goal position. Garoppolo stared down pressure, saw safety Taylor Rapp widened too far and nailed his target in a critical situation. 

"We knew we just had to stay the course, really," Garoppolo told reporters after the game. "It wasn't like they were doing anything to really take away what we were trying to do. We were just killing ourselves." 

Prior to the final drive, Garoppolo had completed only 14 of 24 passes for 182 yards.

Yes, every franchise wants its quarterback to make plays in crucial moments. But the Niners might not have needed his last-second heroics had he performed better earlier in the night.

To be fair, the offensive line is a major area of concern. The Rams sacked Garoppolo six times, and he isn't exactly Lamar Jackson or Russell Wilson behind center. His game will suffer when he gets skittish, much like any other quarterback. Help isn't necessarily on the way, either. 

Center Weston Richburg's season-ending patellar tendon injury may be the most impactful malady any unit suffers during these late stages of the regular season. 

Shanahan's offense is predicated on establishing the zone stretch. To do so, the pivot must regularly be able to accomplish two goals. First, the center is often asked to double-team with the guard to hook the play-side defensive tackle. Second, he must take proper angles for second-level blocks and create the massive cutback lanes often seen in San Francisco's scheme. 

Ben Garland is solid, but he's a guard by trade and isn't the same caliber of an interior blocker as Richburg. On top of that, the 10-year veteran had multiple poor snaps during Saturday's contest. 

Meanwhile, right guard Mike Person continues to deal with a neck injury. He was active Saturday, but Daniel Brunskill started in his place. Brunskill can play nearly every position along the offensive line and has this season. Rams defenders overwhelmed him multiple times, though. 

A weak offensive interior will have significant repercussions for both the ground and aerial attacks. 

The 49ers can normally lean on their defensive front to make everything better. However, it hasn't been quite as effective as of late.

Rams quarterback Jared Goff does a great job getting the ball out when pressured. He'll take every throwaway a blitzing defender will give him. The Niners didn't sack him a single time Saturday.

San Francisco's ferocious front—which can still be highly effective with the pressure it generates—has managed only three sacks since December started. The group is accustomed to getting home, yet it has been shut out in two of the last three games. 

Adjusted game plans are part of the reason for the dip in production. A great play-caller like Rams head coach Sean McVay can use the defensive line's aggressiveness to his advantage. He did a wonderful job of using a combination of rollouts, play action, screens and fake tosses to keep the 49ers off balance.

"I think we made some adjustments [at halftime], which I think was definitely needed," Shanahan told reporters. "From what I saw in the second half, it looks like we slowed them down a number of times on those rollouts. They had a good plan for us." 

For the most part, Goff looked comfortable in the pocket and threw for 323 yards and a pair of scores. That's problematic for the 49ers, because a lack of consistent pressure and a quarterback in rhythm will exploit a questionable secondary. 

The 49ers entered Saturday with the NFL's No. 1-ranked pass defense, but safety Jaquiski Tartt (ribs) wasn't active. Last week, Richard Sherman (hamstring) and K'Waun Williams (concussion) didn't play. The defensive backs room is banged up. As a result, they aren't going to be as effective, especially if the front isn't applying as much pressure as the entire defense has grown to expect. 

Every NFL season is a battle of attrition. Every team has similar issues at this point in the season. The Niners found ways to overcome their injuries in recent weeks, though the level of difficulty is much higher at this point.

They're working their way through these difficulties, which signals one of two things. Either San Francisco hardens itself in the face of adversity for what could be a fantastic playoff run, or pieces of the roster will flake off and create insurmountable damage.  

The 49ers are built to overcome, but opponents don't need Death Star-like schematics to find the team's weak spots. 

Brent Sobleski covers the NFL for Bleacher Report. Follow him on Twitter @brentsobleski.