The San Francisco 49ers' transition to a new defensive coordinator in Steve Wilks hasn't gone as smoothly as planned, with their struggles so obvious that he and Kyle Shanahan agreed to a change for the Week 10 matchup with the Jacksonville Jaguars.

Wilks, having called plays from the booth for the entire season to this point, will move down to the field on Sunday in Jacksonville. The switch follows a three-game losing streak in which the Niners defense has fallen well short of its usual standards, particularly in the defeats to the Minnesota Vikings and the Cincinnati Bengals.

The 49ers have given up 1,186 yards over their last three games, 852 coming in the previous two against the Vikings and the Bengals, with a defense that was firmly in the NFL's elite last season now ranked 15th by DVOA, though it is still 10th by Expected Points Added per play and Success Rate.

Wilks has faced criticism for coverages that seem out of sync with the defensive front, which has struggled to turn pressures into sacks, and a lack of disguise in his play-calling. He also accepted blame for a zero blitz call at the end of the first half versus the Vikings that saw the 49ers surrender a touchdown in a game they lost 22-17.

But the veteran coach is unfazed by the critics and is ardent in his belief he and his defense will come through a rough patch.

"I can honestly say I'm sort of built for this," Wilks told a press conference on Thursday. "Not in an arrogant way but I've always believed there's two things: There's what you hear and what you listen to. 

"I hear a lot of the outside noise and I don't listen to it, good or bad. … I've seen this, I've been around this, I can take it. 

"I'm the new guy here. It is what it is. I have confidence in myself, most importantly I have confidence in those players and the coaches that we're together and we are going to come through this."

As for the attention on his move down to the field, Wilks doesn't understand the level of interest.

"To me, just very candid, I think we are making a bigger deal out of it than it needs to be, to be honest," Wilks said. 

"I just want to be able to communicate with the guys a little bit more during the game. Certain things I’m seeing, I’d rather be able to talk to them directly, than communicate with coaches."

The hope appears to be that Wilks' presence on the sideline will help him better communicate adjustments to linebacker Fred Warner. Many of the problems for the 49ers' defense are simply a matter of execution and have nothing to do with Wilks' location in the stadium. That said, if the change does not deliver the desired results, the criticism of the Niners' defensive coordinator will grow increasingly pointed.

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