After five games on the sideline, Arik Armstead will make his return for the San Francisco 49ers in the divisional round, and the timing could not be better. 

Defensive tackle Armstead has not played since Week 13 because of knee and foot injuries, and it is no overstatement to say he could play a decisive role in the 49ers’ ability to hold off the upstart Green Bay Packers.

Prior to knee and foot injuries ending his regular-season involvement, Armstead was enjoying his best campaign since the 2019 season that saw the 49ers reach the Super Bowl. Armstead had 10 sacks and 11 quarterback hits that year. 

In the 2023 season, he has formed a dynamic interior pass rush duo with Javon Hargrave. Both Armstead and Hargrave rank in the top six among interior defensive linemen with at least 200 pass rush snaps in Pro Football Focus pass rush grade, while they are each tied 11th in PFF's pass rush productivity metric, which measures pressure on a per snap basis.

In pursuit of Love… and Jones

Reuniting that partnership will be especially important against a quarterback in Jordan Love who thrived against the Dallas Cowboys in large part through his ability to extend plays under pressure. 

If Nick Bosa and Co. can get pressure off the edge and Hargrave and Armstead push the pocket consistently from the middle, the avenues for Love to escape the pocket and make the spectacular off-platform throws that defined his remarkable playoff debut will be fewer.

But his return is particularly well-timed because it comes as the 49ers get set to face a running back in Aaron Jones whose three-touchdown performance in the Packers' win over Dallas marked his fourth successive 100-yard game. 

Green Bay led the NFL in rushing Expected Points Added per play over the final three weeks of the regular season, presenting a potential mismatch problem for a 49ers defense that surrendered 115.4 rush yards per game of the final five weeks of the season without Armstead.

But Armstread's recovery — he practiced in full for successive practices on Wednesday and Thursday and does not carry an injury designation for the game — will raise hopes of a resurgence in that area of the game when they need it most. Before his injury, the 49ers were allowing an average of just 79 yards per game, tied with the Chicago Bears for the fewest in the NFL.

It's difficult to definitively identify Armstead's absence as the reason for the 49ers' drop-off in run defense, but his on-off splits further illustrate his importance to the defense.

With Armstead on the field, the 49ers EPA per play on defense was minus 0.14 — negative numbers indicate better defensive performance — while without him it was 0.02, according to Sumer Sports (h/t Akash Anavarathan).

The #49ers' most valuable defender this season was Arik Armstead.

Armstead ON the field: -0.14 EPA (really good)
Armstead OFF the field: +0.02 EPA (above average)

His return should be a huge boost to the defense (especially against the run).

— Akash Anavarathan (@akashanav) January 16, 2024

A huge physical presence at 6ft 7in and 290 pounds who does an excellent job controlling the leverage battle and holding his ground against double teams, Armstead can play a pivotal role in taking away the interior running lanes that Green Bay has flourished in attacking this season and forcing the Packers to be one-dimensional.

Said linebacker Fred Warner: "Arik's been a huge piece of what we do for a really long time here, especially in the run game, and this was, I think, his best year playing the run and the pass on the interior as he's played his entire career here. So it'd be a huge get for us."

Arik Armstead isn't anywhere near the tackle at the end of this play, but he and Nick Bosa are probably the primary reasons why this stop happens.

His return so critical to the 49ers' run defense. pic.twitter.com/Zfgwecl8Jc

— Nicholas McGee (@nicholasmcgee24) January 18, 2024

Refreshing the rotation

As Nick Bosa articulated, there is another facet of Armstead's return beyond his play as a pass rusher and a run defender that figures to be significant, his reintegration into the defense allowing the likes of Javon Kinlaw and Kevin Givens to rotational roles to which they are more suited than the heavy loads taken on by the starters.

“It’ll be huge,” Bosa said of Armstead’s return. “I was really happy with how Javon [Kinlaw] and Kevin [Givens] played last game, so having Arik back and having those two kind of back to their role of not taking 50 snaps but taking 25-30 will be better for everybody.”

While the secondary has taken huge strides this season, the front has long since been the calling card of San Francisco's defense. 

Facing a quarterback with Love's improvisational abilities and a running back of Jones' caliber, the D-Line has an underrated challenge on its hands. 

Refreshed from the bye after a Week 18 game in which they rested starters, it is a position group that should be rejuvenated for that test, but there is no boost greater than the return of Armstead, with the franchise's longest-tenured player arguably among the most critical to their hopes of finally claiming the franchise's sixth Super Bowl title.

49ers’ heaviest advantage vs. Packers has nothing to do with bye week

They must capitalize.