DETROIT (AP) - DETROIT (AP) — The San Francisco 49ers got off to an uncharacteristically strong start. They scored a touchdown on offense in the opening quarter for the first time this year and matched a season high for first-half points.
It was a much different picture in the second half, and mistakes in all phases of the game led to a 32-17 loss to the Detroit Lions on Sunday.
The 49ers (4-11) dropped their third straight game and have lost five of six overall under first-year coach Jim Tomsula.
Matthew Stafford's 1-yard TD pass to Calvin Johnson gave Detroit a 12-point lead one play after Tramaine Brock was called for pass interference in the end zone. During the drive, the 49ers were flagged for being offside or in the neutral zone for the seventh time, giving the Lions a first down and setting a single-game high by an NFL team this year, according to STATS.
"It makes it very difficult, especially on third down when we have a chance to get off the field and we shoot ourselves in the foot," linebacker NaVorro Bowman said. "The penalties we caused on our own. This comes to discipline and focusing on your assignment.
"I believe I said, 'Watch the ball,' about 50 to 60 times after we jumped off about five times."
San Francisco turned the ball over on downs on its next two possessions.
The 49ers became the first team to have six offside or neutral-zone penalties in the first half since 1993, when the Houston Oilers did it against New Orleans, according to STATS. On special teams, they allowed Detroit to convert a fake punt, missed a field goal and negated a pair of 30-plus yard returns in the closely contested first half with penalties.
"Going into halftime we felt good about where we were other than those offside penalties," Tomsula said.
San Francisco was flagged 11 times for the second straight week.
"For the life of me, I can't give you an excuse," Tomsula said.
Detroit (6-9) has won five of their last seven games, perhaps giving coach Jim Caldwell a chance to keep his job for a third season.
Blaine Gabbert threw for two TDs, both of which gave San Francisco a lead, but his fumble let the Lions take the lead for good midway through the second quarter. Gabbert finished 22 of 33 for 225 yards.
Joique Bell's 1-yard run gave Detroit a 17-14 lead one play after Gabbert lost the ball on a sack.
Stafford was 29 of 37 for 302 yards. Johnson, possibly playing his last home game with the Lions because they may cut him to manage their salary cap, had six receptions for 77 yards.
San Francisco's Anquan Boldin became the 13th NFL player with 1,000 career receptions on the first play of the game.
"At this point, it doesn't mean much," he said. "I'd much rather take the win."
Boldin caught all five of the passes thrown his way for 27 yards in the first quarter and wasn't targeted by Gabbert the rest of the game.
"They played the same defense," Boldin said. "Nothing changed."
DuJuan Harris, signed by San Francisco on Tuesday off Baltimore's practice squad, ran for a career-high 73 yards while replacing injured running back Shaun Draughn. Harris had 74 yards on nine carries in the first half when the 49ers trailed 20-17, and then carried the ball just two more times in the second half.
"Teaching pass protection to a running back in a week is a big deal," Tomsula said.
Harris helped San Francisco to a relatively successful first half before fading into the background.
"We got up on them, so they had to throw more," Lions defensive end Darryl Tapp said. "When you make teams play one-dimensional football, you give yourself a better shot to win."
NOTES: Vance McDonald and Torrey Smith had TD receptions for the 49ers. ... San Francisco DT Quinton Dial left with a back strain.
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