49ers vs. Cardinals: 5 reasons San Francisco lost in Week 8

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GLENDALE, AZ – OCTOBER 28: Wide receiver Christian Kirk #13 of the Arizona Cardinals scores the game winning touchdown over cornerback Jimmie Ward #20 and defensive back Tyvis Powell #30 of the San Francisco 49ers during the fourth quarter at State Farm Stadium on October 28, 2018 in Glendale, Arizona. (Photo by Christian Petersen/Getty Images) /

No. 2: Injuries in the 49ers Secondary

It’s been a theme all season, but injuries continue to plague San Francisco.

Linebacker Reuben Foster suffered a hamstring injury late in the second quarter, but that didn’t appear to hinder the defense’s efforts.

What did, however, was the game-ending loss of safety Jaquiski Tartt to a shoulder injury.

Tartt recorded an interception in the game — only the second pick the 49ers defense has generated this season. But he also came out of the game just before halftime, which forced backup defensive back Antone Exum into the fray.

But then Exum suffered a concussion and had to come out. Enter third-string safety Tyvis Powell, and the Cardinals made sure to take advantage of that matchup as much as possible.

Powell allowed the Cardinals’ first fourth-quarter touchdown — a 13-yard connection from Josh Rosen to Larry Fitzgerald, where the defensive back was late in picking up his receiver:

Powell also gave up Arizona’s game winner too.

If football is all about exploiting matchups, Byron Leftwich did a better job finding these than Kyle Shanahan in Week 8.