Since traveling out west and holding the 49ers to 303 yards of offense – evening their record in the process – the Bucs defense has come apart in the last two weeks.

The Raiders and Falcons both have far better offenses than San Fran, to be sure, but not so much better that Tampa Bay should allow 1,123 yards combined. Oakland quarterback Derek Carr threw for a franchise-record 513 yards in Week 8, while Atlanta’s Matt Ryan, who threw for 344, looked well on his way before being pulled in the final quarter of Thursday night’s 43-28 win.

Releasing the ball quickly, often over the middle to wide open receivers, both signal-callers were sacked twice – over a combined 96 drop-backs.

Friday, head coach Dirk Koetter was asked plainly, ‘Why is the defense struggling?’

“We’re not communicating well enough,” Koetter said of the unit that ranks 25th in the NFL in pass-defense. “Not everybody’s able to just line up and read their keys and play fast. That’s what you want to do with every position and we’re just not doing that right now. It could be different reasons on different plays. We’re talking about communicating all the time and making sure everybody’s on the same page, and we’re not doing a good enough job of that right now.”

To illustrate Koetter’s point, consider this: Lavonte David, the team’s leading tackler since his rookie year in 2012, had 69 stops through eight games last season. This year he has 44, with just 10 in consecutive losses at home against Oakland and Atlanta.

That could be the result of a system that doesn’t feature the weakside linebacker as heavily – middle linebacker Kwon Alexander has 72 tackles, fifth-most in the NFL – but the Bucs star players’ roles either seem to be minimized or difficult to adjust to. Whatever the case, the end result is glaring. Tampa Bay has seen an overabundance of explosive plays and a lack of turnovers to make up for them.

For a young team learning a new scheme, the problem could be that the defense is missing an identity. Koetter conceded just that, saying it’s his job to fix.

“I think every team finds its own identity sooner or later,” Koetter said. “Sometimes what you think you’re going to be when you start the year, it doesn’t work out that way, for one reason or another.

“I think that might be a fair assessment, that maybe we haven’t really found what we can consistently hang our hat on,” he said. “There are different reasons for that. All that is, that’s our job as coaches. That’s my job, to help us get to that point.”