The 49ers’ Biggest Weakness

It's important to remember they've lost three of their past four games, and one weakness in particular lies hidden just beneath the surface.

The 49ers just beat Jacksonville by 31 points, so they don't appear to have any weaknesses right now. But it's important to remember they've lost three of their past four games, and one weakness in particular lies hidden just beneath the surface.

Cornerback Ambry Thomas. He's the No. 3 cornerback, and he plays on the right side in the nickel defense while starter Deommodore Lenoir moves inside to cover the slot.

Thomas is so bad, he got benched at halftime of the first game of the season and replaced by Isaiah Oliver, who's a nickelback. So with Oliver on the field, Lenoir would stay outside in the nickel defense. This was the 49ers lineup until the bye week, and somehow it was even worse than the original. Oliver was horrendous in man coverage, zone coverage and defending the run -- he was just terrible. And so the 49ers benched him during the bye week and brough Thomas back into the fold.

And Thomas made a nice play on Sunday against the Jaguars when he forced a fumble and recovered it. But in coverage, he's a spectator at best and a penalty waiting to happen at worst. He gave up two catches and committed a 23-yard pass interference penalty against the Jaguars, who don't have an elite wide receiver. Teams that do have elite receivers, teams such as the 49ers' upcoming opponent, the Buccaneers, who have Mike Evans, surely will go after Thomas. And he might not hold up.

If he doesn't, the 49ers can activate Samuel Womack or Darrell Luter Jr., who are returning from injuries, and hope for the best.