SANTA CLARA – Something is wrong with the 49ers’ defense.

For example, look at their run defense. Running back James Connor failed in the first half last Sunday against the Cardinals. Only gave up 9 yards on 6 carries. Complete domination.

But in the second half, the Cardinals made an adjustment and suddenly the 49ers couldn't stop Connor. After halftime, he sprinted 75 yards.

What happened?

“They gave us a different look at the zone read,” Nick Bosa said. “For all our losses, the preparation we had was great, but teams play us differently and do things differently and we need to adapt a little better. They simply present a different look than what we have seen.” Volume. We have to adapt.

When Bosa says “we” need to adapt a little better, he means defensive coordinator Nick Sorensen. He is responsible for the defense's in-game adjustments, as are head coach Kyle Shanahan and associate head coach Brandon Staley. The brain trust.

As expected, Shanahan disagreed with Bosa's assessment. In a conference call Monday morning, Shanahan pointed out the poor run defense to his players.

“I know the long touchdown run we had,” Shanahan said. “If you play in an eight-man front and the defense misses, you're a man short and your middle third player has to make the tackle and he's been buried. That would have been a big win, but not.” A touchdown win and he was buried in that too. When you have an eight-man front and no one is responsible for the quarterback, having one man in lane isn't necessarily a mistake, which definitely helps with these things. There's always give and take when you play a system where the quarterback can make it. I don't fall asleep on any play the entire game because you never know when he's going to make it. And if you don't have a player account for it and they have the kind of speed that a quarterback has, then that's the case. We were there about two times in the game. That was the worst. Then we hurt again in the fourth quarter.

So Shanahan blames the players. Bosa blames the coaches. And the 49ers are 2-3.

Seems like things aren't going well behind the scenes.

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