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Film Review: How third-down struggles have plagued 49ers defense

© Kirby Lee-USA TODAY Sports

With all of the 49ers’ defensive issues — missed tackles, untimely penalties, and blown coverages, to name a few — they have had plenty of chances to get off the field on third down throughout the past three games. The Kansas City Chiefs scored touchdowns on each of their first five drives in Week 3 largely because the 49ers could not force fourth downs, even with favorable opportunities. Defensive coordinator Robert Saleh highlighted third-down defense as an area of emphasis entering San Francisco’s Week 4 matchup with the Los Angeles Chargers.

“It comes down to tackling and third down,” Saleh said last Thursday. “It is that simple.”

The 49ers actually improved in third-down defense in last Sunday’s 29-27 loss, allowing four conversions on 14 attempts. They forced fourth downs on Los Angeles’ final five third-down plays. But all three of the Chargers’ touchdowns came on third down, which, in a two-point final result, stings.

Things started smoothly for the 49ers as they jumped out to a quick 14-0 lead. On the first third down of the game, 49ers strong safety Antone Exum returned an interception— San Francisco’s only of the season— for a touchdown. The 49ers did not allow a point on their first three defensive possessions. Defensive end Solomon Thomas and linebacker Reuben Foster got backfield pressure, and the secondary covered well.

But the Chargers started moving the ball effectively late in the first quarter. On the their first scoring drive, the Chargers had third and goal at the San Francisco five-yard line. Chargers running back Melvin Gordon and tight end Antonio Gates ran crossing routes. 49ers cornerback Ahkello Witherspoon stuck with Gordon, and Foster detached from Gates to follow Gordon, leaving the Pro Bowl tight end with acres of open land. Chargers quarterback Philip Rivers floated the easy touchdown to Gates, who stood a whopping 13.62 yards from the closest defender, according to NFL Next Gen Stats.

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These miscommunication issues— a hallmark of a young, inexperienced team — have plagued the 49ers defense all year long.

On their second touchdown of the day, the Chargers had third-and-3 at the San Francisco 22-yard line.

They split running back Austin Ekeler out wide, leaving 49ers linebacker Fred Warner with a tough one-on-one assignment. It was the matchup the Chargers wanted. On the television broadcast, you can see Rivers glance to his right side pre-snap. Ekeler made one move, blew by Warner, and Rivers dropped in a perfect touchdown throw.

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Fast forward to the 10:40 mark in the third quarter. For the third time Sunday, the Chargers scored a touchdown on third down. They had third-and-4 at the San Francisco six-yard line.

The Chargers split out five receivers. The 49ers played a soft zone. Witherspoon retreated into the end zone, not accounting for the first-down marker at the two-yard line, and Gordon curled there unoccupied. Rivers had plenty of time to hit Gordon for the easy score.

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San Francisco’s lack of a pass rush was its most glaring weakness entering 2018. The front office did little to address it in the offseason, trusting that its current rotation of defensive linemen would produce. But the 49ers have yielded just eight sacks all season, including one last Sunday. DeForest Buckner, the team’s best player, had 3.5 sacks in the opening two weeks, but teams have consistently doubled him, and the defensive ends haven’t won their one-on-one matchups. That has allowed opposing quarterbacks to sit in the pocket and pick apart the 49ers defense.

As last Sunday’s game progressed, however, the defense improved.

Midway through the third quarter, the 49ers got backfield pressure on another third down in the red zone. The play was well-covered, and Rivers had minimal time to survey his options. He threw the ball out of bounds. The Chargers settled for a field goal.

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The 49ers defense started and ended well but struggled mightily in the second and third quarters. A similar theme of inconsistency held true in Week 3, when the 49ers allowed 35 points to the Chiefs in the first half and just three points in the second half.

What bothered Saleh is that the 49ers had at least one opportunity for a third-down stop on each of Kansas City’s five touchdown drives. It did not happen. The Chiefs converted seven of their 11 third-down plays into first downs or touchdowns on the day.

Their first conversion of the game came on third and 15 in the first quarter. Saleh blitzed free safety D.J. Reed and nickelback K’Waun Williams. Chiefs head coach Andy Reid called the perfect counter, dialing up a screen play that yielded just enough yardage for a first down.

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On the ensuing drive, the 49ers forced third and 16. Chiefs quarterback Patrick Mahomes sailed a throw out of bounds to receiver Chris Conley. But Williams was flagged for a questionable pass interference call, spotting the ball on the San Francisco goal line. The Chiefs ran in a touchdown one play later.

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One of the top plays of the NFL season came with nine minutes remaining in the second quarter. The Chiefs had the ball on third-and-goal at their own four-yard line. Mahomes retreated, then ran in a circle— as if he was rotating a controller’s joystick on Madden— before whipping a touchdown pass to Conley. The 49ers never touched Mahomes. 49ers safety Adrian Colbert bumped into a teammate in the back of the end zone, leaving Conley running free.

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On the final two drives of the first half, the 49ers forced third-and-short situations. But they jumped offsides both times, extending the Chiefs’ drives, which resulted in touchdowns.

These third-down issues have made life very hard for a young defense. It seems this unit has a few cornerstones to build upon, including Buckner, Foster, Warner, and Richard Sherman. They have shown flashes, but they have struggled to close out drives. Their opponents have converted on 43.1 percent of third-downs, the 12th-best mark in the NFL.

The 49ers coaching staff highlighted third-down efficiency last week. By the numbers, both the offense and defense improved in Week 4, but the Chargers’ three touchdown scores on third down played a deciding role in the final result.

“We need to get better at tackling, first and foremost, and do better at third down on defense, also,” Kyle Shanahan said last week. “I think both sides of the ball, first thing, if we could get off the field on third down on defense and we could stay on the field on offense on third down, I think that would change a lot of things dramatically.”


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