Glendale, AZ — The San Francisco 49ers just lost 47-24 to the Arizona Cardinals. Here are the 49ers’ grades for this performance.

QUARTERBACK: D

Joshua Dobbs turned the ball over three times and was one of the main reasons the 49ers lost. He’s not a good backup quarterback and the 49ers should not re-sign him this offseason. And yet, he led the 49ers offense to 24 points on the road while playing with backups and against the Cardinals starters. As opposed to Brock Purdy, who led the 49ers’ starters to just 23 points at home against Arizona in Week 5. If Brock Purdy truly is worth $60 million per season, the offense would perform much better with him on the field than with Dobbs on the field, but it doesn’t. The 49ers need to keep their options open at quarterback. Extending Purdy to a big-money deal would be a huge mistake. This season exposed Purdy for what he is — a liability in the second half of close games.

RUNNING BACKS: A

Isaac Guerendo left the game early with an MCL injury — he may not be durable enough to succeed as an NFL running back. To be determined. After he left the game, Patrick Taylor Jr. replaced him and gained 109 rushing yards on 17 carries. No matter who the running back was this season, the 49ers were able to rush the ball effectively, which makes this 6-11 season all the more baffling.

FULLBACK: A

Kyle Juszczyk caught a 36-yard touchdown pass when he was wide open in what hopefully was his final game with the 49ers.

WIDE RECEIVERS: B

Jauan Jennings got ejected after committing personal fouls on back-to-back plays. After the game, instead of taking responsibility for his penalties, he said that the referees made a mistake. He seemed pleased with himself despite his team losing its seventh game in the past eight weeks. The 49ers are so undisciplined. Meanwhile, Ricky Pearsall had another good game — 6 catches for 69 yards and a touchdown. If only the 49ers had gotten him involved earlier this season, they might have won more than six measly games.

TIGHT ENDS: C

George Kittle played half the game and finished with 27 receiving yards. After the game, he said he’s going to talk to Kyle Shanahan tomorrow about Shanahan’s performance this season. When I asked Kittle how he thought Shanahan did this season, Kittle said he’d save his thoughts for Shanahan. Sounds like Kittle has something serious to say.

OFFENSIVE LINEMEN: B-PLUS

The 49ers averaged 4.9 yards per carry and Joshua Dobbs got sacked only twice. Not a bad performance considering all the backups who are starting for this unit.

DEFENSIVE LINEMEN: F

Went through the motions and sacked Kyler Murray zero times.

LINEBACKERS: F

Went through the motions and gave up 5.6 yards per carry against an offense that was missing its starting running back.

DEFENSIVE BACKS: F

Went through the motions and gave up 4 touchdown passes and a 128.5 passer rating to one of the most inconsistent quarterbacks in the NFL.

SPECIAL TEAMS: F

Played like they usually do, which means they got burned by a fake punt and Jake Moody missed his weekly field goal. How many games would the 49ers have won this season if their kicker were anyone else?

COACHES: F

The defense simply stopped playing for Nick Sorensen. Three weeks ago when the season was on the line, the defense gave up just 12 points in a loss to the Rams. Then the 49ers were eliminated from playoff contention. Since then, the defense has given up 116 points in the final three games. Shameful. The 49ers have no choice but to fire Sorensen now. Clearly, promoting Sorensen to defensive coordinator was one of Kyle Shanahan’s biggest football sins of the year. But Shanahan’s football sins were numerous. In today’s game, his team committed a whopping 13 penalties while the Cardinals committed just one. That’s because the Cardinals are well-coached and the 49ers are not. Shanahan can blame this humiliating season on injuries, but he should blame himself. His utter refusal to honestly assess himself and hold himself responsible for the Super Bowl collapse is precisely how the 49ers scapegoated Steve Wilks, replaced him with Sorensen and ended up 6-11. Now Shanahan has to figure out what went wrong, and his analysis must begin with a deep dive into himself. Will his ego allow him to look in the mirror, or will he continue to blame others for his failures? We’ll find out.