SANTA CLARA, Calif. – Matt Breida saw Pierre Garcon have his defender pretty well blocked. It’s what a running back loves to see, a receiver downfield blocking – only this was a little bit different than normal. What was happening against the Detroit Lions on Sunday afternoon was a little bit stronger.

See, Garcon blocked Nevin Lawson for almost a quarter for the field. It was one elongated block on one big play, but it exemplified so much about where Detroit’s run defense is. Breida hadn’t seen a block that far downfield go for that many yards in a long time.

“Not since Little League,” Breida said. “So you got to be definitely more patient in the NFL. Guys are faster. They are smarter. I just feel like we had a great game.”

Breida was “amazed” at the block – and it even allowed him to pause to let Garcon set up the final part of the block to finish off Breida’s 66-yard touchdown run, another big play surrendered by a Lions defense that struggles handling the run.

For the second straight game, an opposing running back scored a touchdown on a 60-plus yard run to the outside. On Sunday it was Breida starting around the right tackle before cutting all the way across the field to the left. In Week 1 it was Isaiah Crowell running around the right end for a 62-yard touchdown.

Both came in the third quarter. Both started around the same spot. And being able to get outside was something San Francisco saw in its game plan earlier in the week as something it could exploit – similar to what the Jets said after beating the Lions in Week 1, where they ran almost an identical play to an outside run Oakland scored with in the preseason.

“We kind of knew that was a weakness in their defense, getting outside runs,” Breida said. “So you know, that’s kind of what we focused on. Not all of our outside runs [Sunday] hit outside. Some of them bounced back inside.

“So we just took whatever they gave us.”

What they gave was a lot – 190 yards rushing, six days after the New York Jets rushed for 169 yards. Through two weeks (with one game left to play), the Lions are allowing 179.5 rushing yards per game – worst in the NFL by 25.5 yards. The 5.61 yards per rush allowed are second-worst in the league to Oakland (5.7).

The big plays, for the Lions, have been the killer against the run.

“It’s just big plays we’re giving up,” defensive lineman Ricky Jean Francois said. “We’re right there. It’s not like we can’t stop the run. It’s just little plays, just here and there, that we’re not either making the tackle or we’re not in our gaps or we're just shooting ourselves by not doing our assignment.

“I take the blame on that [Breida run], forget everybody else around me. I knocked the guy back so far I couldn’t see where he was at and he hit the gap I was responsible for, he hit the C gap, so that one’s on me.”

It’s the big plays, though, that will doom a team. Jean Francois admitted as much. So did his coach, Matt Patricia, who lamented the Lions giving up too many run plays. Three of San Francisco’s top five plays Sunday, yardage-wise, were runs by Breida of 20 yards or more. Defensive back Quandre Diggs called the big-play runs “frustrating.”

“If you get one run for whatever it is, 60 or 70 yards, obviously that’s going to be a problem,” Patricia said. “Not good enough. I have to coach it better. ... So that’s on me.”

A lot of Lions were taking the blame for the big runs – from the defensive linemen (Jean Francois) to the secondary (Diggs) to the coaches (Patricia). It’s not clear why it keeps happening. Just that it is happening.

The Lions have been in a tough run defense spot before. The unit struggled during the second half of last season (before finishing No. 27 in the league against the run). Eventually, just by law of averages, the big runs will stop. When that happens, though, will be up to how Detroit tries to handle it.

Because they know what to do. And they know if they don't fix it, teams will keep running on them all year long. The Jets, and then the Niners, proved that.

“We all have to take pride in it and we just have to get it fixed,” Diggs said. “I don’t know what magic words you guys want me to say. It’s nothing magical.

“We just have to get 11 guys to the ball and make the tackles.”