Do the 49ers have a problem defending mobile quarterbacks?

As the 49ers prepare for the postseason, there is a growing sentiment from 49ers fans that the defense struggles to contain mobile quarterbacks. It’s easy to understand why, as the Niners haven’t had success this season in the win/loss column against quarterbacks that are a threat to run.

The 49ers’ four losses on the season have come against mobile quarterbacks. The difference between the four quarterbacks is Justin Fields and Marcus Mariota are running Quarterbacks, while Russell Wilson and Patrick Mahomes are quarterbacks who can run.

Here’s a look at the rushing yards allowed in the four games:

Justin Fields - 11 rushes for 28 yards with a long run of 12.

Russell Wilson - Six rushes for 17 yards with a long run of 12.

Marcus Mariota - Six rushes for 50 yards and a touchdown with a long run of 20.

Patrick Mahomes - No rushing line.

At first glance, these numbers aren’t impressive or concerning. Jalen Hurts and Daniel Jones are much more runners than Dak Prescott. If both teams advance, the 49ers wouldn’t contend with Hurts until the NFC championship game.

Looking back on the Denver and Kansas City game didn’t show too many plays of concern. Denver scored nine points on offense. The Chiefs hurt the 49ers through the air due to coverage busts.

Let’s look back at the two games with true running quarterbacks.

Week 1 - Chicago

The weather was a factor in Week 1. The messy weather tilts things towards the rushing attack. Another factor to mention is in Week 1, Chicago had far fewer designed runs in the game plan for Fields. There are zone reads sprinkled throughout the game, but Fields was unleashed with designed runs as the season progressed.

Here are five plays from Week 1:

The jet motion, coupled with the play fake, gets the 49ers flowing in the opposite direction of Fields. The result is an easy eight-yard gain. Darnell Mooney is designed to be the target, but Fields sees green grass and takes it.

On the very next play, here’s an example of great discipline by Drake Jackson. Jackson doesn’t bite one way or another on the fake and brings Fields down for a small gain.

Samson Ebukam has this play dead to rights, but Fields’ athleticism is too much. Have to tip your cap to Fields on this play. First down for the Bears as Fields makes something happen.

Cover your eyes, 49ers fans. Showing both angles of this play is important. Fields avoids the sack by Arik Armstead and gets outside of the pocket. The defense reacts to the threat of Fields’ mobility and loses Dante Pettis.

We can argue who is responsible for who in this play; the bigger point is the entire defense reacted to Fields. This play comes down to discipline, in my opinion.

As the pocket collapses, Fields breaks contain for a gain. Ebukam has no chance in a foot race. Keeping Fields in the pocket is the goal, but it didn’t happen on this play.

Takeaways:

The touchdown on the busted coverage is the most concerning. Other than that, the 49ers did a great job containing Fields.

Week 6 - Atlanta

Nick Bosa, Arik Armstead, Javon Kinlaw, and Azeez Al-Shaair all missed this game. Not to mention, Mooney Ward and Talanoa Hufanga left the game with injuries. Hufanga returned, but Ward did not.

The Falcons punished the 49ers on the ground, but Mariota had some back-breaking gains.

The edge defender bites on the zone read, and Mariota plays it to perfection. Leaving the edge defender unblocked puts the decision in Mariota’s hands leading to an easy gain.

This play is back-breaking. As the pocket collapses around Mariota, the middle of the field opens up with nothing but green. Gaining 13 on third down is the stuff nightmares are made of for defenses—credit to Mariota for sliding in the pocket to avoid Charles Omenihu and then doing the rest.

Jet motion again gets the 49ers flowing in the opposite direction. From there, it’s simply a numbers game as Mariota easily beats Samuel Womack to the edge for the touchdown. Credit to the play design on this one.

Discipline, again, comes back to bite the 49ers. Samson Ebukam bites on the zone read, and Mariota tucks it for a big gain. To be fair, the Falcons had the run game going all game, and Ebukam was looking to make a play. Just a bit over-aggressive.

Here’s an example of Ebukam not biting on the fake and stopping the run attempt dead in its tracks. Great pursuit from the backside to end this run before it begins.

Takeaways:

The 49ers were missing impact players in Week 6. Still, the defense was a bit overly aggressive as the Falcons’ rushing attack thrived.

In conclusion, I don’t believe the 49ers are in trouble facing running/mobile QBs. DeMeco Ryans spoke at length at yesterday’s press conference about discipline from his defense. Running QBs in the NFL presents problems for any defense. It’s hard to walk away thinking this is some “fatal flaw” for the 49ers. A little discipline and patience will go a long way for this defense.

Do you believe the 49ers have a problem slowing running QBs?