This stat shows just how valuable Nick Bosa is to the 49ers

This is incredible.

Joe Nicholson-Imagn Images

The San Francisco 49ers are officially feeling the impact of losing Nick Bosa on defense. The team had a strong effort when they initially lost him, but they did not have the depth and talent to survive the wear and tear that the league brought on them. 

San Francisco 49ers pass defense struggles without Nick Bosa

The loss of Bosa has not impacted the run game too much. According to RBSDM, the 49ers rushing EPA/play was -0.106 with Bosa in the first three wees, but it has been -.170 without him. The success rate jumped from 41.6% to 43.5%.

Still, the most notable difference is the pass defense. The 49ers defense went from 10th in EPA per play, allowing -0.014, and 14th in success rate at 45% all the way to 0.284 in EPA and 53.2% in success rate. That is 29th and 28th, respectively. They went from above average to quite possibly the worst in the NFL.

With Matthew Stafford and Baker Mayfield, the 49ers have played some strong quarterbacks without Bosa, but this was a defense that held Sam Darnold in check, and he is one of the hottest quarterbacks in the NFL.  

It did not help that Warner also went down, but the issues in pass defense were showing with Wanrer. The issue was the pressure was not present. 

Sergio Estrada-Imagn Images

When Bosa is on the field, the 49ers pressure rate is 33.6%, but without him it is 23.1%. Losing Bosa pushed the 49ers to play both Yetur Gross-Matos and Bryce Huff more. Gross-Matos was playing through an injury and was hardly practicing, so the ramp up in snaps resulted in a hamstring injury. Huff went from rotational to nearly full-time, and he got banged up. 

There is no sign that the 49ers will get either of those two back in the next week or so, and this may be what causes the team to make a trade a week before the deadline rather than waiting. The 49ers cannot lean on Trevis Gipson and Robert Beal and expect to get a pass rush that gives their secondary a chance. 

When the pass rush is strong, the secondary has proven that they can hold up their end. When it looks like Sunday, CJ Stroud will pick this secondary apart with rookies and no name wide receivers. The 49ers are in a tough spot, and without a pass rusher to step up, nothing is going to change.