What we learned in the Rams’ 33-7 loss to the Baltimore Ravens

Here are the takeaways from the Rams’ preseason game against the Baltimore Ravens, a 33-7 loss.

Sean McVay is not taking chances with injuries

Kicker Greg Zuerlein’s back injury notwithstanding, the Rams got through the 2017 season without many key starters suffering major injuries.

Offensive linemen no doubt played through any number of issues, but none sat out games because of them, enabling running back Todd Gurley and quarterback Jared Goff to flourish.

So McVay is accustomed to working with a healthy roster. He needs one if the Rams are to live up to their lofty expectations.

The Rams appeared to have emerged without any significant injuries after practicing twice with the Ravens. McVay said he had planned all along to rest his starters in the preseason opener.

He stuck to his plan and kept 22 on the sideline.

Sean Mannion needs a fair shot with front-line players

The backup quarterback struggled against the Ravens, completing only three of 13 passes for 16 yards, with an interception. He was sacked twice, and the Ravens deflected several passes at the line of scrimmage.

It was Mannion’s first game since his start against the San Francisco 49ers in the regular-season finale. With starters sitting out to avoid injuries before the playoffs, Mannion completed 20 of 34 passes for 169 yards and was sacked three times in a 34-13 defeat.

Goff, the Rams’ starter, is a rising star coming off his first Pro Bowl appearance. There is no quarterback competition. This certainly is not a call for one.

But if McVay truly wants to assess Mannion’s ability to lead in the event of a Goff injury, let him play behind a line anchored by left tackle Andrew Whitworth. Let him hand the ball off and throw screen passes to Gurley. Let’s see if he can accurately deliver the ball to receivers Robert Woods, Cooper Kupp and Brandin Cooks.

Mannion, in the final year of his contract, might struggle in those scenarios as well. But his chances for success — and a realistic evaluation of his capability — are exponentially greater playing with the proven starters.

Offensive line depth could be an issue

Guard Jamon Brown, suspended for the first two regular-season games but eligible to play during the preseason, was the only starter who played on offense.

With Whitworth and starting right tackle Rob Havenstein on the sideline, Darrell Williams and Cornelius Lucas were listed as starters. And the Ravens got constant pressure off the edges.

Rookie Joseph Noteboom said he played a series at right guard but also played tackle. He needs time to mature. He might have to do it quickly.

Adjustment to new rules will take time

Rams players were called for lowering their head twice during a Ravens’ first-half scoring drive.

Safeties Marqui Christian and Blake Countess each drew 15-yard penalties that helped the Ravens move down the field.

All NFL players are getting used to the rule, and officials are aggressively calling it so that players can adjust.

Sitting starters keeps them safe, but it also prevents them from real-time exposure to situations they can learn from before making costly mistakes when games count.

Young linebackers were active

Draft picks Micah Kiser and Trevon Young made six and four tackles, respectively. And undrafted free agent Tegray Scales had five tackles.

Ejuan Price, a seventh-round draft pick in 2017, had a sack.

Lamar Jackson is fun to watch — and difficult to tackle

Jackson, the 2016 Heisman Trophy winner, probably cannot stay out of harm’s way in the NFL if he scrambles like he did in college at Louisville, and as he attempted at times during no-tackle practices with the Rams.

On Thursday night, that didn’t stop Jackson from faking out three would-be tacklers on a nine-yard touchdown run against the Rams.

With Jackson and Robert Griffin III playing well, the Ravens are three-deep at quarterback.

gary.klein@latimes.com