Can 49ers' offensive line make progress in 2019?

SANTA CLARA - When Bill Walsh was alive, he often said the quarterback defines the limit of an offense, determines how good it can be.

Last season, the 49ers lost their starting quarterback, Jimmy Garoppolo, to a torn ACL during the third game of the season. His absence was a major reason the 49ers won just four games in 2018, and his performance this season largely will determine if the 49ers make the playoffs - simply because he's the starting quarterback.

But Garoppolo won't perform well if his offensive line doesn't protect him. He needs help, especially during his first season back from a major leg injury. Pass protection will define Garoppolo's limit and the limit of the 49ers' offense this season.

The 49ers believe they have a good offensive line. It's the 10th-most expensive one in the NFL, with all five starters under contract through 2021. But it struggles in pass protection. Last season, the 49ers gave up 48 sacks (ninth most in the NFL) and 125 quarterback hits (second most). The strength of the line is run blocking, which doesn't help Garoppolo.

Here's what each starting offensive lineman has to prove heading into training camp:

Right tackle Mike McGlinchey

McGlinchey has to prove he's not a turnstile.

He already has proven he's a terrific run-blocker. The 49ers took McGlinchey with the ninth pick in the 2018 draft specifically to replace Trent Brown, who didn't fit the 49ers' outside-zone blocking scheme. They traded him to the New England Patriots a day after drafting McGlinchey.

When Brown was the 49ers' right tackle in 2017, they averaged just 3.1 yards per carry running behind him around the right end. With McGlinchey at right tackle in 2018, the 49ers averaged a whopping 5.34 yards per carry around the right end.

But McGlinchey gave up 12 sacks in 16 games. A turnstile. With the Patriots, Brown allowed just four sacks in 19 games, counting the playoffs and the Super Bowl, which the Patriots won.

Now, Brown is an Oakland Raider, and the highest-paid offensive lineman of all time. A man at the peak of his craft. Meanwhile, McGlinchey is a young player who needs to make a big leap forward.

“Overall strength (was an issue),” McGlinchey said during minicamp. “It's just about being a little bit more physical in pass protection, being the controller in pass protection.”

McGlinchey believes he will improve.

“I'm coming into a situation where I have a full grasp of what's going on with the offense and what's being told to you and how you're being coached and all the calls that need to be made and the defenses in front of you,” McGlinchey said. “Having a whole year under my belt makes things a lot easier.”

Right guard Mike Person

Person has to prove he's not a one-year wonder.

He was supposed to be the backup center last season, and Joshua Garnett was supposed to be the starting right guard. Garnett is a former first-round pick. Person is a former seventh-round pick who had never started a game at guard entering last season.

But Garnett injured his foot Week 1. This injury kept him out until Week 4. When he finally returned, he didn't get his starting job. Person had taken it.

Person turns 32 on July 17. He's not a great run blocker and not particularly big or strong for an offensive lineman, which explains why he has played for six franchises. But last season, he gave up only four sacks - the fewest of the 49ers' five starting linemen. Person was in the zone.

The 49ers expect he will stay in the zone - that's why they gave him a three-year, $8.25 million contract extension this offseason. “Aside from his toughness and durability, he brings tremendous versatility to our offensive line,” general manager John Lynch said in a statement. “Mike is exactly the type of person and competitor we look for.”

If Person reverts to the person and competitor he was before last season, Garnett may get another chance to play.

Center Weston Richburg

Richburg has to prove he can stay healthy.

Last season, he missed just one game. But he tore his quadriceps tendon during Week 4, played through the injury and struggled big time. Richburg gave up nine sacks in 15 games. Defensive linemen routinely overpowered him.

Richburg will turn 28 on Tuesday, and hasn't been injury free since 2016. In 2017, he suffered a concussion and missed 12 games as a member of the New York Giants. After the season, the Giants made no effort to re-sign him. Apparently, they felt he was injury prone. They might have been right.

The 49ers weren't concerned about Richburg's health, so they gave him a five-year, $47.5 million contract in 2018.

“Didn't know a ton about him until I turned on the tape, and it was as good as I've seen,” Shanahan said when the 49ers signed Richburg. “You've got to do your homework and check into the guy. From everything we found out, he's off the charts.”

The 49ers need Richburg to stay off the charts.

Left guard Laken Tomlinson

Tomlinson has to prove he can block rushers who don't line up directly in front of him.

Tomlinson won the Bobb McKittrick Award last season for representing “the courage, intensity and sacrifice displayed by the 49ers' longtime offensive line coach.” Tomlinson's fellow offensive linemen were the only voters. Clearly, they respect him, as does the front office.

“We're thrilled with what he has become,” Lynch said in April.

Tomlinson, 27, blocks well during run plays and pass plays. He's strong and athletic, and can move the defensive lineman directly across from him. He's a former first-round pick.

But Tomlinson gave up seven sacks last season, because pass rushers don't always rush straight ahead. Sometimes they move around during the play, and Tomlinson struggles to block moving targets. That's why he gave up five sacks during a three-game stretch in December before tearing his MCL in the season finale.

The league may have figured out how to attack Tomlinson in pass protection. He needs to adjust and continue improving.

Left tackle Joe Staley

Staley has to prove he's not declining.

If George Seifert still were the 49ers' head coach, he probably would have gotten rid of Staley by now. Seifert had no sentiment for older players. He traded Joe Montana when he was 36 and got rid of Ronnie Lott when he was 31. Seifert would rather cut a player one year too early than one year too late. This was the philosophy Seifert learned from Walsh, who also lacked sentiment for older players.

The current 49ers regime does not share this philosophy. Staley will turn 35 in August, and the team recently gave him a two-year contract extension through 2021.

“He has gotten better since we've gotten here, which is very exciting, especially at his age,” Shanahan said in June.

Staley was excellent in 2018. The 49ers averaged 5.32 yards per carry when running behind him, and he allowed just 4½ sacks. But he showed his age when he had to change directions, so defensive ends occasionally beat him to the inside when they rushed the passer.

“I did a lot more yoga and mobility stuff (this offseason) than in years past,” Staley said. “As I get older, I need to make sure my hips, ankles and knees (are OK).”

Staley, the model of a proud, stoic 49er, remains optimistic about the offensive line as a unit.

“It's going to be the first time in a while we've had all five starters come back from last season,” Staley said. “That's nothing but positive.”