Grant Cohn: Why the 49ers will win their season finale

When the 49ers beat the LA Rams this Sunday, remember this column.

It says here the 49ers will win 19-17, despite missing three running backs, three wide receivers and a quarterback, and playing a 12-win team that can't take the day off. This game is really important to the Rams. They could blow their first-round bye in the playoffs if they lose to the 49ers.

Oddsmakers predict the Rams will win by 10 points.

Here's why the oddsmakers are dead wrong:

1. They underestimate the 49ers' defense.

The oddsmakers expect the Rams to score exactly 29 points, and it's easy to see why:

The 49ers' defense has allowed 30.3 points per game on the road this season.

But that stat is misleading. In each of the 49ers' seven road games, either Reuben Foster or Malcolm Smith played weak-side linebacker and both were awful. Foster couldn't remember the play call consistently, and Smith couldn't move well — he had an Achilles injury.

Now, Foster is on the commissioner's exempt list while cashing checks from the Washington Redskins and Smith is on the bench. And suddenly, the 49ers' defense plays with discipline. Because the new weak-side linebacker, Elijah Lee, isn't bad. In fact, he may be the best linebacker on the team.

Isn't it amazing how many good players the 49ers didn't know they have?

Lee has started four games. And with him in the lineup, the 49ers defense has given up just 19.5 points per game. He allows the defense to function. Without him, it's chaos.

The Rams will have to grind to score points against the new, improved Niners.

2. Jared Goff is a pedestrian quarterback right now.

Earlier this season, Goff was superhuman when he had his slot receiver, Cooper Kupp, who is a terrific player. Goff trusts him more than any other receiver.

But Kupp is out for the season with a torn ACL. And his injury hurts Goff.

When Kupp was healthy, Goff's quarterback rating was 118.1. Since Kupp has been out, Goff's quarterback rating is merely 86.6.

The 49ers will double-cover both of the Rams' outside receivers — Robert Woods and Brandin Cooks — and take away the play-action deep passes to force Goff to patiently check down to his tight ends. Goff hates checking down and he's not patient. He will force passes into coverage.

The Rams will have to run the ball well to win.

3. Todd Gurley will miss the game with a knee injury.

When the 49ers and Rams played at Levi's Stadium on Oct. 21, Gurley scored three touchdowns and the Rams won 39-10.

With Gurley out this Sunday, the Rams' starting running back will be C.J. Anderson, whom they signed off the street less than two weeks ago.

In his first game with the Rams last Sunday, Anderson rushed for 167 yards and one touchdown. But he faced the Arizona Cardinals, who have the NFL's worst record and seem to have quit on their head coach, Steve Wilks. The Cardinals reportedly will fire him at the end of the season, according to ESPN's Adam Schefter.

The 49ers have not quit on Kyle Shanahan. They will play hard against the Rams, and shut down their fill-in running back.

4. The Rams have major issues in their secondary.

Defensive tackles Aaron Donald and Ndamukong Suh are fantastic players. But even with those two rushing the quarterback, the Rams' defense has allowed an average passer rating of 94.1 this season.

Their two veteran cornerbacks, Marcus Peters and Aqib Talib, have not played consistently well. And their free safety, LaMarcus Joyner, will miss Sunday's game with an ankle injury.

Last season, Joyner injured himself against the 49ers, and the Niners went on to score 39 points in that game with Brian Hoyer as their quarterback. Joyner is important to the Rams' defense.

Without Joyner on the field, Nick Mullens should have an easier time against the Rams' secondary.

5. Someone unexpected will have a big game for the 49ers.

To take advantage of the Rams' weak secondary, the Niners need receivers who can get open, and may not have any.

Dante Pettis, Marquise Goodwin and Pierre Garcon all will miss Sunday's game. Which means the 49ers' No. 1 receiver will be Kendrick Bourne, who has 33 catches this season. And their No. 2 receiver will be rookie Richie James, who has six catches.

The outlook for the passing game seems bleak.

But almost every time the 49ers lose someone, they promote someone else who turns out just as good as or better than the player he replaced.

Mullens, Lee and running back Jeff Wilson Jr. are three prime examples. The 49ers had no idea how good they were until they had to play. If the 49ers knew what they had, those backups would have played much sooner.

This week, the 49ers promoted undrafted rookie wide receiver Steven Dunbar Jr. from their practice squad. Shanahan said Dunbar will play against the Rams. Mullens said he has better chemistry with Dunbar than any other receiver on the 49ers. Those two spent lots of time together on the scout-team offense during practices.

Dunbar will make the game-winning touchdown catch and the 49ers will enter the offseason feeling good about themselves. Not a bad end to the season.

Grant Cohn covers the 49ers and Bay Area sports for The Press Democrat and pressdemocrat.com in Santa Rosa. You can reach him at grantcohn@gmail.com.