SANTA CLARA, Calif. — Losing both offensive tackles could have sunk the 49ers.

Instead, it made them tougher.

The 49ers (5-0) have continued to roll even though left tackle Joe Staley missed the last three games with a broken fibula and right tackle Mike McGlinchey missed the last game with cartilage damage in his knee.

Their replacements, Daniel Brunskill and Justin Skule, haven’t been spectacular but they have helped the 49ers remain undefeated.

“The two rookies did a great job stepping in and filling their roles,” quarterback Jimmy Garoppolo said. “Those guys are just battling up front. What they do in the run game and pass game is so impressive.”

Brunskill and Skule have replaced two of the best starting tackles in the NFL. McGlinchey and Staley are highly talented former first-round draft picks, and Staley is a six-time Pro Bowler. Brunskill and Skule don’t have much pedigree. Skule is a rookie sixth-round pick, and Brunskill was an undrafted free agent in 2017.

“They are both pretty quiet,” Garoppolo said. “They will talk when they are in the conversation or something like that. On the field they’re different, though. It’s so cool, that dog that comes out in them. Screaming at people, in a good way.”

Third-year tight end George Kittle frequently lined up next to Brunskill and liked the right tackle’s consistency. “I guess that’s all you can really ask for when you’re replacing McGlinchey,” Kittle said. “Dan went in there and did his job and did it well. No mistakes.”

Brunskill spent the last two seasons on the Falcons practice squad, then played this spring for the San Diego Fleet in the now defunct Alliance of American Football. The 49ers signed him April 12. Since then, he regularly has picked the brains of Staley and McGlinchey.

“They see things you might not have seen about a guy that’s rushing against you,” Brunskill said. “Mike is a younger guy, so he can help me with different things he has been learning. Then you also have Joe, who knows everything and has seen it all.”

Skule played college football at Vanderbilt. He made his second career start at left tackle in last weekend’s 20-7 victory over the Rams and gave up one sack to perennial All-Pro Aaron Donald.

“Obviously, a lot to fix,” Skule said. “I gave up the sack and a couple other pressures. Definitely a ton to learn from.”

Skule was hard on himself but coach Kyle Shanahan gave him and Brunskill positive reviews for their performances against the Rams.

“They weren’t perfect the entire game, but they’re one of the reasons we won. They allowed us to run it and they played with toughness,” Shanahan said. “It’s a very tough position to be in, especially (against) some of those pass rushers.

“They got Donald one-on-one on Skule on the very first pass play, and he ended up giving up a sack. A lot of guys giving up a sack in a big game like that, they can kind of melt. They can lose their confidence and it takes some time to get it back. Skule went right back out there the next third down and did a good job blocking.”

The 49ers hope Staley will return in Week 9 and expect McGlinchey to return between Week 9 and Week 11. Until then, the 49ers will embrace the challenge of playing without them.

”I think it has made our offense tougher,” Shanahan said. “The guys are a lot more resilient. I think the guys start to develop the mentality that it doesn’t matter who’s out there. It’s been a credit to our guys that they’ve been able to get that confidence now going on for a few weeks. We’re going to need that to keep going for a few more weeks until we get some of these guys back.”