The 49ers’ PFF grades for their 24-23 loss to the Arizona Cardinals on Sunday at Levi’s Stadium show an alarming trend that the team must curb.

Three turnovers by the offense ultimately made a win impossible for San Francisco, but their 12 missed tackles, after 17 missed tackles the week before, are a troubling statistic for a defense that is routinely touted as one of the best in the league.

49ers missed tackles per week:

Week 1 vs. New York Jets: 9

Week 2 vs. Minnesota Vikings: 3

Week 3 vs. Los Angeles Rams: 2

Week 4 vs. New England Patriots: 17

Week 5 vs. Arizona Cardinals: 12

Defenseman Nick Bosa led the pack with three missed tackles on Sunday, according to PFF. While the All-Pro had standout plays in other areas of the game, including four stops, two pressures and an interception, the pass rusher’s mistakes didn’t help the defense get off the field.

Rookie safety Malik Mustapha, who came into the game for Talanoa Hufanga after the veteran suffered a wrist injury, missed two tackles, as did linebacker De’Vondre Campbell. Hufanga, safety Ji’Ayir Brown, cornerbacks Deommodore Lenoir and Charvarius Ward and defensive tackle Kevin Givens were all charged with one missed tackle each.

In the 49ers’ Week 4 win over the New England Patriots, Bosa was again charged with three missed tackles, as was Campbell. Brown, Lenoir, linebacker Demetrius Flannigan-Fowles and defensive tackle Maliek Collins were each charged with two missed tackles, while Mustapha, Ward and cornerback Renardo Green each missed a single tackle.

If the 49ers want to keep their playoff hopes alive, they will have to figure out a way to eliminate or at least reduce the number of missed tackles in games.

Here are the 49ers’ PFF grades for Week 5:

Ddefense

DL Nick Bosa — 87.9

While the pass rusher was charged with missing three tackles (25.6 tackle grade), Bosa made up for it in other areas. The All-Pro recorded four tackles: all solo, four stops and two hurries.

DL Leonard Floyd — 79.1

The pass rusher recorded three pressures: one sack, one hit and one rush, while also recording three stops and no missed tackles.

Remaining Quarterback Pressure:

S Ji’Ayir Brown – one rush

DL Sam Okuayinonu – one rush

DL Kevin Data – one rush

DL Maliek Collins – one rush

CB Deommodore Lenoir -74.3

The cornerback allowed one catch on three targets for three yards and one pass breakup. Lenoir also returned the blocked field goal kick for a touchdown.

CB Isaac Yiadom -76.4

Yiadom is improving in the 49ers system, recording two tackles (one assist), one stop and one forced fumble. The defensive back also allowed one completion on two targets for 14 yards and one pass breakup.

Defensive odds and ends

Cardinals running back James Conner was stopped in the first half and recorded just nine yards on six carries, but it was a different story after halftime. Conner carried the ball 13 times in the second half for 77 yards. 74 of Conner’s 86 rushing yards came after contact, and he forced eight missed tackles on the day.

The 49ers blew on 12 of Murray’s 32 dropbacks (37.5 percent), which is higher than their 31st-ranked 19 percent through the first four games.

Ooffence

WR Brandon Aiyuk – 90.0

Aiyuk’s overall grade of 90.0 topped the team after he caught eight of his 11 targets for 147 receiving yards, six of which resulted in a first down. The wideout caught all three of his targets for 41 yards while in the slot.

TE George Kittel -72.4

Kittle caught eight of his 12 targets for 64 yards and a touchdown, with five of his catches resulting in a first down or a touchdown.

RB Jordan Mason – 57.2

Mason would have received a much higher score had he not scored in the red zone in the fourth quarter. The Georgia Tech product recorded 14 carries for 86 yards, 72 of which came after contact.

Mason currently leads the NFL with 340 rushing yards after contact, 25 missed tackles forced and 16 runs of 10 or more yards.

QB Brock Purdy -73.7

Purdy completed 19 of his 35 attempts for 244 yards, one touchdown and two interceptions. Using play action, Purdy completed six of his eight attempts for 97 yards and a passer rating of 115.1. Without game action, Purdy completed just 13 of his 27 attempts for 147 yards, one touchdown, two interceptions and a 46.4 rating.

Purdy’s sweet spot was intermediate throws that ranged from 10 to 19 yards down the field. On Sunday, he completed just eight of his 15 attempts at that distance, or 53.3 percent, after completing 10 of 19, or 77.8 percent, in the first four weeks.

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