Do the 49ers Have a Weakness?

For years, the 49ers had the same three glaring weaknesses: Cornerback, offensive line and quarterback. Now, the 49ers have improved at all three positions.

Brock Purdy is a huge upgrade over Jimmy Garoppolo -- that's obvious. What's less obvious is how the cornerbacks and the offensive line have improved.

The first half of the season, the cornerbacks were awful. They got completely embarrassed a few weeks ago against Joe Burrow and the Bengals. But during the bye week, the 49ers benched nickelback Isaiah Oliver, whom they signed during the offseason. A big mistake they finally acknowledged -- he's allowing a passer rating of 105 on an elite defense. He's the weak link.

Now he's on the bench, Deommodore Lenoir covers the slot and Ambry Thomas is the No. 3 cornerback in the nickel defense. And suddenly the secondary is playing well. Thomas intercepted a pass against the Seahawks and is allowing a passer rating this season of 87, which is respectable. Meanwhile, both Lenoir and Charvarius Ward are allowing passer ratings below 80, which is good. So now there's no clear weak link to pick on.

The offensive line doesn't seem to have a weak link, either. It used to be right guard Spencer Burford, but Jon Feliciano started there on Thanksgiving and played well. The 49ers would be wise to keep him there, because the right side of their offensive line has been awful for years. It caved in during the Super Bowl loss to the Chiefs, and it caved in during the NFC Championship loss to the Rams.

With Feliciano, it won't cave in. The 49ers finally seem like they've addressed every weakness on their roster. Now Kyle Shanahan has zero excuses if he loses the Super Bowl. He needs to close the deal this season.

Can he?