Defense gets lift with return of Reuben Foster

San Francisco 49ers linebacker Reuben Foster (56) celebrates on the sideline during the fourth quarter against the Los Angeles Chargers at Levi's Stadium.Photo: Kelley L Cox-USA TODAY Sports

When there are 22 players on the field at a time, how much of a difference can one guy make?

The San Francisco 49ers will find out this week when a Kansas City Chiefs offense ranked in the top 10 in the NFL in rushing, passing, total offense and scoring encounters a defense ranked in the bottom half of the NFL across the board.

With one difference: The 49ers will have linebacker Reuben Foster this week.

The former Alabama standout returns from a two-week suspension for Sunday's game at Kansas City, and head coach Kyle Shanahan is so thrilled that he doesn't know what to do with him.

That's because the 49ers have allowed the 14th-most rushing yards in the league through two weeks despite one opponent having been the Detroit Lions, who ranked dead last in the NFL in rushing last season.

San Francisco has allowed the eighth-most passing yards despite also having played the Minnesota Vikings, who weren't a top-10 team in passing last season.

So the versatile Foster, who made starts at both middle and outside linebacker as a rookie last season, could prove helpful at either spot.

Which leads to Shanahan's giddiness.

If only there were two of Foster.

"Everyone knows how good of a tackler he is," Shanahan observed. "But he's also good in coverage. He can blitz the quarterback. He can do a lot of things. Just having his presence out there, just from a leadership standpoint, guys gravitate to him. We really enjoy having him around."

The 49ers also are hoping to get another starting linebacker, Malcolm Smith, back in action this week after he missed the first two games with a hamstring injury.

Smith, like Foster, has demonstrated an ability to play inside and out.

Mix in rookie Fred Warner, who has manned the middle the last two weeks and leads the team with 19 tackles, and you can understand why Shanahan isn't quite sure where to line up Foster against the Chiefs.

"Reuben hasn't been here in two weeks (and Wednesday was) going to be Malcolm's first day of full practice," Shanahan said before Wednesday's workout, the team's first since a 30-27 home win over Detroit. "So we want to see how all of those guys do and it'll be a tough decision at the end of the week, but a tough decision I'm going to be happy to have to make.

"We don't have the plan yet. We've got to see how they are, how they play. The plan is to do whatever we think gives us the best chance to win."

SERIES HISTORY: 13th regular-season meeting. 49ers lead series, 7-5. The home team has won the last nine meetings dating to 1982. The 49ers captured the most recent contest 22-17 in San Francisco in 2014, while the Chiefs prevailed 31-10 in 2010 in the most recent matchup in Kansas City. The clubs have never met in the postseason, but do have one famous regular-season meeting -- when Joe Montana (203 yards, two touchdowns) and Steve Young (288 yards, two interceptions) went head-to-head in a 24-17 Chiefs home win in 1994. Marcus Allen rushed for the difference-making touchdown that day.