49ers 33, Dolphins 17: Grades

That's what you call a statement win.

SANTA CLARA -- The 49ers just destroyed a playoff team with their third-string quarterback. That's what you call a statement win. Now they've won five games in a row and their record is 8-4. Here are the 49ers' grades for their 33-17 win over the Miami Dolphins.

BROCK PURDY: B

Jimmy Garoppolo left the game after the first series with a broken foot -- he's out for the year. Which means he may have played his final game with the 49ers, and now the team belongs to Brock Purdy, at least until the end of the season. And in this game, the offense performed quite well with Purdy -- certainly no worse than it had been performing with Garoppolo. For a rookie who was the last pick in the draft, Purdy showed surprising poise and confidence on the field. He also moves better than Garoppolo and throws downfield better than him, too. Plus, Purdy likes to line up under center and turn his back to the defense unlike Garoppolo, which means the 49ers actually will have a play-action passing game the rest of the season -- that's a good thing. But can the 49ers actually win the Super Bowl with Purdy? Maybe not, but he also can't play worse in the playoffs than Garoppolo has played in his six postseason starts, so don't count out the 49ers just yet. They still have the best defense in the league. Call me cooky, but I'm starting to think the defense, not Garoppolo, is the reason the 49ers have won so many games the past few seasons.

RUNNING BACKS: A

Christian McCaffrey gained only 3.9 yards per carry, but the Dolphins never figured out how to cover him as a receiver, so he torched them with eight catches for 80 yards and a touchdown. McCaffrey is an absolute pleasure to watch run routes. And his backup, Jordan Mason, is outstanding. He averaged 6.4 yards per carry against a defense that was selling out to stop the run. He looks like a young Marshawn Lynch. He deserved more than the eight carries he got. And Deebo Samuel needs to stop playing running back. Today he ran the ball four times for five yards. The wide-back experiment is over. The 49ers have two good running backs -- McCaffrey and Mason. They don't need to hand off to their highest-paid wide receiver anymore.

WIDE RECEIVERS: C

Deebo Samuel had 58 receiving yards and no touchdowns -- not exactly what the 49ers are paying him nearly $24 million per season to produce. And Brandon Aiyuk had just five catches for 46 yards. Forgettable game for these two.

TIGHT ENDS: C-MINUS

George Kittle had 22 receiving yards and a holding penalty -- not exactly what the 49ers are paying him $15 million per season to produce.

OFFENSIVE LINEMEN: D

Their pass protection was not good -- they gave up four sacks and got one quarterback injured -- and their run blocking was even worse. The running backs got hit behind the line of scrimmage repeatedly. The 49ers need to overhaul this unit in the offseason.

DEFENSIVE LINEMEN: A-PLUS

They dominated an offensive line that was missing both starting tackles and made Tua Tagovailoa seem skittish in the pocket all game. Nick Bosa in particular recorded 3 sacks, 4 quarterback hits, 2 tackles for loss and a forced fumble. And the 49ers pay him only roughly $8 million per season. What a bargain.

LINEBACKERS: A-PLUS

Dre Greenlaw made a team-high eight tackles and scored a touchdown, and Fred Warner recorded an interception that sealed the victory. They have to be the best linebacker duo in the NFL.

DEFENSIVE BACKS: A-MINUS

Deommodore Lenoir and Jimmie Ward each intercepted a pass, which is extremely impressive, but the 49ers won this game with their pass rush. The Dolphins had open receivers running through the secondary all game -- Tagovailoa just missed them. He must have airmailed at least five wide-open receivers in this game. Give the 49ers pass rush credit for making him seem so uncomfortable, but a better quarterback with a better offensive line would have hit some of those throws -- that's what Patrick Mahomes did to the 49ers more than a month ago. We'll see how they perform next week against Tom Brady.

SPECIAL TEAMS: A

Ray-Ray McCloud had a 20-yard punt return, Robbie Gould made all four of his field goal attempts and Mitch Wishnowsky pinned the Dolphins inside their 20-yard line twice.

COACHES: A

DeMeco Ryans' defense dominated one of the best offenses in the NFL. The defense gave up a 75-yard touchdown pass on the first play of the game, then gave up just 10 points the rest of the way. Extremely impressive, and yet not surprising, because the 49ers have the best defense in the league. Call it Alcatraz. No escapes. Teams better have a fully-healthy offense and an all-time-great quarterback when they visit The Rock, or else they'll get locked up. The 49ers offense still isn't great -- today it averaged just 4.4 yards per play -- but they had to switch quarterbacks on the fly. And Garoppolo and Purdy are different. Which means Kyle Shanahan deserves credit for adjusting midgame and calling plays that suited Purdy's skillset. Notice Shanahan  called more pocket movement and play-action passes for Purdy than he had been calling for Garoppolo. It seemed like Shanahan finally got to call the offense he wants to run, not the one Garoppolo wants to run. Perhaps Purdy will unlock Shanahan's creativity the rest of the season.