49ers report card: Grades for offense, defense in Week 1 loss to Bears

CHICAGO — The natural grass at Soldier Field has widely been known for years as a poor surface in inclement weather.

However, when the weather turned bad on Sunday, the newly rolled-out Bermuda grass held up a lot better than the 49ers in the regular-season opener.

The 49ers got washed away in a 19-10 loss to the Bears in a game that featured costly penalties, turnovers and just plain sloppiness.

Defensive end Nick Bosa described the team’s inability to come away with a victory as “annoying.” There are plenty of other ways to sum it up.

And here are the grades that capture their rough Week 1 performance:

Rushing offense

The 49ers figured to lean heavily on their running game, and that’s what they did. San Francisco pounded the Bears on the ground in the first half with 115 yards and a 6.4-yard average. Elijah Mitchell exited in the first half with a knee injury.

Wide receiver Deebo Samuel scored the first touchdown of the game on a 6-yard run.

But he also made the first costly mistake of the game when he fumbled on a running play in the second quarter when the 49ers moved the ball to the Chicago 12-yard line.

The 49ers found the yards a lot more difficult to achieve in the second half but still finished with 176 yards rushing and a 4.8 average.

Quarterback Trey Lance was the 49ers’ leading rusher with 54 yards, while Samuel gained 52 yards.

Grade: B-minus

Passing offense

Lance, making his first start after officially taking over for Jimmy Garoppolo, had an up-and-down game. He opened his press conference with a listing of the mistakes he made, including an overthrow of tight end Tyler Kroft on what should have been an early touchdown.

When the 49ers were playing from behind in the fourth quarter, Lance did not see Bears safety Eddie Jackson. That interception gave the Bears a short field that was used to tack on a touchdown for a nine-point lead.

The elements played a part in this game. Lance completed 13 of 28 passes for 164 yards. But Lance took full responsibility.

Jauan Jennings was the team’s leading receiver with four catches for 64 yards. Brandon Aiyuk caught two passes for 40 yards, and Lance hooked up only twice with Samuel (on eight attempts) for 14 yards.

Grade: D-minus

Rushing defense

The 49ers’ run defense was solid from start to finish. Chicago running back David Montgomery had a particularly difficult time finding any room to run. He was held to just 26 yards on 17 rushing attempts.

The Bears gained 99 yards on 37 rushing attempts. Khalil Herbert averaged 5.0 yards per attempt and gave Chicago a nine-point lead with a 3-yard touchdown run midway through the fourth quarter.

The 49ers had six tackles for loss, including two from strong safety Talanoa Hufanga. He had a team-high 11 tackles, and linebacker Fred Warner added six tackles.

But the 49ers also had some mistakes as part of their run defense. Dre Greenlaw was called for two penalties: unnecessary roughness and face mask. Both calls were questionable.

But there was no question about a mistake from Azeez Al-Shair, who delivered a late hit on a sliding Justin Fields for a 15-yarder.

Grade: B-plus

Passing defense

The 49ers…