For the past half decade, the 49ers and Rams have never been boring.

That did not change on Sunday, in a 30-23 49ers win that was the ninth-straight regular season victory for San Francisco over Los Angeles.

For the entire first half, this thing was an offensive slugfest; neither defense was capable of getting a stop. But Isaiah Oliver, the much-maligned nickel signing this offseason, made two key plays in the second half that changed the tide for San Francisco.

Isaiah Oliver’s redemption

The 49ers signed Isaiah Oliver to a two year, $6.75 million deal this offseason to be their starting nickel after losing Jimmie Ward to the Texans in free agency.

In training camp and the preseason, he looked lost. He was missing tackles, getting beat in coverage by players (Keelan Cole Sr.) who failed to make their 53-man roster, and eventually lost the starting nickel job to Deommodore Lenoir.

It was a worrisome proposition. Did he just need time to adjust to the defense? Would he never get it?

On Sunday, he made a case that he was getting it, and probably won back the job that was gift-wrapped for him this offseason.

After a first half in which the 49ers defense looked incapable of stopping the Rams, Oliver ensured they got a stop. On a third-and-5, he wrapped up Kyren Williams on a short reception to the left, setting up a 4th-and-2 and eventual punt.

The next drive, after a rare three-and-out for the 49ers offense, the Rams looked set to take the lead. Oliver had other ideas. Williams whiffed on a short pass and Oliver pounced on it heroically, for this one-handed interception:

It fundamentally changed the game. San Francisco got a 57-yard field goal from Jake Moody after another Purdy miss, and came back down for a touchdown. A potential Rams lead quickly became a 10-point 49ers lead.

He also put the nail in the coffin for the Rams in the fourth quarter. On a 4th-and-1 at their own 39-yard line, the Rams handed off to Williams. Oliver shot his gap and spun Williams down in the backfield, all but ending Los Angeles’ distant hopes of late heroics.

Brock Purdy’s inaugural Rams matchup, and three bad misses

We had all gotten so used to Brock Purdy slinging it, that watching him make some Jimmy Garoppolo-esque mistakes was a bit jarring.

There were three of those misses from Purdy:

1. 2nd and 9, LA 45, 7:57 remaining in Q1: Purdy had Brandon Aiyuk streaking down the right sideline on a double move. Aiyuk, after a neck/shoulder injury, was returning to the field and had separated in acres of space. Purdy badly overthrew him and had to scramble to get back to the line the next play. It became a punt. The Rams took a 17-10 lead on the next drive.
2. 3rd and 7, SF 21, 9:02 remaining in Q3: This was a potentially massive gain. Again, Purdy overthrew his target, lofting it over Jennings’ head. It almost set up a Rams lead, if not for Oliver’s interception.
3. 3rd and 7, LA 32, 1:32 remaining in Q3: This was a touchdown. Samuel won outright. Purdy threw too far instead of leading him over the middle. Jake Moody’s 57-yard field goal bailed him out.

Despite all that, Purdy is clearly an upgrade over every other quarterback the 49ers have had with Kyle Shanahan. He executes on all the so-called layup throws, can make off-schedule plays, and most of all, as Shanahan says, he “rips it.”

After those misses, you wouldn’t be shocked to see a quarterback lean towards conservatism. Purdy doesn’t seem to have that anywhere in his composition.

At the end of the first half, with 1:45 remaining, he led a ballsy, seven-play, 75-yard touchdown drive that ended with him sneaking the ball in for a touchdown with no time left on the clock.

When he got an opportunity at redemption to start the fourth quarter, he took it. With Sebastian Joseph-Day bearing down on him, Purdy was unflappable. He held in the pocket and found Samuel low for a 16-yard gain.

The very next play, he took a one-on-one shot down the left sideline to Jauan Jennings. He gave him a back shoulder ball where only Jennings — with a clear size advantage over Cobie Durant — could catch it, and did, for an impressive 27-yard gain.

Four plays later, he let Samuel do all the work on a vintage, make-everyone-miss, 11-yard touchdown that put the 49ers up 10 in the fourth.

It should be noted that Purdy had another bad miss on a 3rd-and-2 in the fourth quarter, missing Samuel high and behind him.

As egregious as the misses were — and they were brutal — Shanahan kept letting Purdy sling it, and Purdy mostly obliged.

Defense find its pulse the second half

The 49ers were playing incredibly soft coverage in the first half and their pressure was not getting home. It was a putrid combination.

That totally changed in the second half. Those two Oliver plays ended the first two Rams possessions of that second half.

On the next drive, Steve Wilks dialed up a crucial blitz on a 3rd and 10 situation, with Fred Warner sacking Stafford for a 10-yard loss and three-and-out.

The Rams’ only scoring output of the second half came on their following drive, which went for 14 plays and 56 yards, ending in a 48-yard field goal.

After the nonexistent pressure in the first half, the defensive line started to harangue Stafford with four. That’s the key to the 49ers’ defense, and once Nick Bosa, Arik Armstead, Javon Hargrave and Drake Jackson started to find their groove, the tenor changed.

Almost any notion of a Rams comeback ended with Deommodore Lenoir’s fourth-quarter interception of Matthew Stafford. It set up a 26-yard Jake Moody field goal to put the 49ers up by 10.

That field goal was the only thing the Rams’ offense put on the board in the second half. After being gashed for 196 yards and 17 points on three drives in the first half, they allowed 140 yards and 3 points on the first six drives in the second half.

With the game out of hand, the Rams matriculated the ball down the field in the final two minutes for a 50-yard drive and a hilarious, meaningless field goal as time expired, a dagger to certain bettors.

Other notes: Sloppy snaps, injuries

• Jake Brendel had a snap that hit George Kittle in motion, and luckily ended up in the hands of Christian McCaffrey. He also snapped a ball too early, which ended up on the ground. Brock Purdy jumped on it quickly, but it wasted a down. He seemed preoccupied with Aaron Donald, for obvious reasons.
• Ambry Thomas had a knee injury and returned, and Deommodore Lenoir was evaluated for a concussion, but came back and had a key interception.
• Brandon Aiyuk is the one to watch here. He had a neck/shoulder injury and played limited snaps because of it. That’s one to watch going forward. Deebo Samuel was also in some pain, but played through it.