Grant Cohn: Five keys to determining winner of 49ers-Rams game

Here are five things that will determine the winner of the 49ers' season opener against the Rams. They are the things the coaches are thinking about right now.

1. The 49ers' depleted defensive line.

Last season, the 49ers faced running back Todd Gurley once. Their top-four defensive linemen — Ian Williams, Quinton Dial, Glenn Dorsey and Arik Armstead — all were healthy. None of them could stop Gurley, who rushed for 133 yards and a touchdown.

This season, Dial already has a sprained knee, Armstead has an injured shoulder, Dorsey is recovering from a torn ACL and Williams is out for the season with a broken ankle. The other three didn't participate in 11-on-11 team drills during practice this week and may not play Monday night.

If they Niners couldn't stop Gurley when they were healthy last season, how can they expect to stop him now? They'll need a big game from DeForest Buckner, the rookie first-round pick who seems to be the Niners' healthiest defensive player on their line.

2. The Rams' depleted secondary.

Los Angeles' defense is terrific, but it has a major weakness it didn't have last season. Cornerback.

During the offseason, one of the Rams' starting corners, Janoris Jenkins, signed a five-year, $62.5 million contract with the New York Giants. The Rams intended to replace him with E.J. Gaines, a sixth-round pick in 2014 who broke his foot in 2015 and missed the entire season. The foot is healthy, but now his thigh is not. He pulled it two weeks ago and is out for Week 1.

Without Jenkins and Gaines, the Rams have to start Coty Sensabaugh at corner even though they signed him to play nickel back and cover the opponent's slot receiver. He isn't suited to cover outside receivers. He's too small.

Sensabaugh is the player the Niners' offense should exploit. But exploiting him may not be as easy as it sounds. The Niners have the worst group of wide receivers in the league and a quarterback who prefers passing to running backs and tight ends. Blaine Gabbert doesn't trust his arm to make long throws to wide receivers. He knows he's inaccurate.

Will Gabbert even challenge Sensabaugh? Or will Gabbert let the Rams off the hook?

3. Chip Kelly's run game.

Kelly wants to run the ball 65 percent of the time. That's his formula.

Obviously, he can't accomplish his goal if the Niners fall hopelessly behind. In that case, they will have to pass. But they shouldn't fall hopelessly behind Monday night. The Rams, like the Niners, have a questionable passing attack, meaning neither team should score much. Kelly should be able to run as much as he wants.

And Kelly needs to run the ball to win. During his three seasons as head coach of the Eagles, he won just two games and lost 13 when his offense failed to gain 100 rushing yards.

Will the Niners gain 100 rushing yards Monday night?

4. Carlos Hyde's health.

Most expected the Niners to lose their season opener last year when they faced the Vikings, an excellent team that ended up winning its division.

But San Francisco dominated Minnesota 20-3 in the season opener, and the best player on the field was Carlos Hyde. He rushed for 168 yards and two touchdowns. That was his best game of the season.

Next game, the Steelers knocked out Hyde during the third quarter and he never was the same. The Niners' season quickly fell apart.

Hyde is an excellent running back when he's healthy. He can carry the Niners to a win against the Rams. But Hyde gets injured easily. He already suffered a concussion during the preseason. Can he make it through Monday night's game? Can he run the ball 25 times?

5. Blaine Gabbert's feet.

The Rams have two excellent defensive coaches — head coach Jeff Fisher and defensive coordinator Gregg Williams. They know they have to shut down Hyde to beat the 49ers. They're no dummies.

The best way to shut down Hyde simply is to take the ball out of his hands. And the best way to do that is to force Gabbert to run on the zone-read play.

The zone-read is the basis of Kelly's run game. Here's how the play works: Gabbert reads an unblocked defensive end and, if the defensive end chases the running back, Gabbert is supposed to keep the ball and run.

But Gabbert doesn't want to keep the ball and run. He wants to hand it off. He has very little experience running the zone-read. He's a pocket quarterback who scrambles as a last resort, not someone who likes to keep the ball on designed runs.

Expect the Rams to force Gabbert to run as much as possible. Expect their unblocked defensive end to ignore Gabbert and chase Hyde all night. Will Gabbert take advantage? Can he win the game with his feet?

Grant Cohn writes sports columns and the 'Inside the 49ers' blog for The Press Democrat's website. You can reach him at grantcohn@gmail.com.