Grading 49ers QB Brock Purdy's season with four games left

He won the game, but that's largely because his defense allowed just 13 points. Purdy led the offense to a measly 17 points while throwing 2 touchdown passes and 2 picks. Both interceptions were unforced errors and bad decisions. He was the reason the game was so close. To be fair, he injured his toe in the first half.

And while he gave the 49ers a four-point lead late in the game with a nice touchdown pass to Jake Tonges, the 49ers' defense sealed the victory by stripping the ball away from Sam Darnold on the Seahawks' final drive. The defense won this game.

Week 4 vs. the Jaguars: F

He rushed back onto the field after the 49ers had won two games without him. He wasn't healthy. He reinjured his toe. He turned the ball over three times, completed less than 58 percent of his passes and was the main reason the 49ers lost. Had they started Mac Jones instead, they probably would have won.

Week 11 @ the Cardinals: B-Plus

He threw for a mere 200 yards, but he also threw 3 touchdown passes, zero interceptions, led the offense to 41 points and won. Granted, he beat a team that has lost 10 of its past 11 games, and he threw at least two passes that should have gotten intercepted, but overall, he played well against a bad defense.

Week 12 vs. the Panthers: F

The 49ers won this game in spite of Purdy. He passed for 193 yards, 1 touchdown, 3 interceptions and a passer rating of 58.5 at home. To be fair, the Panthers have a good pass defense that intercepted Matthew Stafford twice last week.

Still, Purdy threw an interception on three straight drives, and all of them were downfield throws he didn't have to make because he was winning. His defense gave up just 8 points in the entire game. All he had to do was check the ball down, and the 49ers would win. And that's all the 49ers let him do in the second half. They took this game out of his hands, which was the merciful thing to do. They could have benched him instead. He deserved it.

Week 13 @ the Browns: B

He beat the Browns in Cleveland, but so did Cam Ward and Carson Wentz. Almost everyone beats the Browns, because they beat themselves.

The best thing Purdy did in this game was not throw an interception. And he accomplished this rare feat by throwing the ball away a whopping seven times. To his credit, he didn't force anything downfield like he did against Jacksonville and Carolina.

Instead, he dinked and dunked, averaged 5.8 yards per pass attempt, converted some third downs and let the defense win the game. The 49ers gave up just eight points.

Composite grade: D-Plus

Fortunately for Purdy, this essentially is his mid-term grade, because he has just five starts under his belt with four left in the regular season. If he aces the next four games, he can raise his overall grade to a B-minus. Not bad considering he has two giant Fs on his report card.

For the past six quarters, the 49ers haven't let Purdy throw the ball down the field to anyone other than George Kittle. We'll see if that continues. Kyle Shanahan is treating him like he's Jimmy Garoppolo, who was a mistake waiting to happen. That's what Purdy has been this season despite his 4-1 record.

If the 49ers are going to win a playoff game this season, they'll need Purdy to raise his performance significantly.