CHICAGO – Growing up 30 miles from Soldier Field, Jimmy Garoppolo occasionally would tag along with his electrician father, Tony, to a side job away from their Arlington Heights home.

"He'd throw a wire down to the basement and say, 'Hey, do you see it down there yet?' " Garoppolo recalled in a May 2019 interview.

The working conditions weren't always favorable, especially in Chicago's cold winters.

"That work ethic is not seen every day and I'm glad I got to witness it firsthand," Garoppolo added. "Anytime you think you're having a rough day, I always think back to that, and I'm like, 'Is it as tough as you think it is?' "

This year's been tough, from the 49ers' wandering eye (see: Matthew Stafford, Deshaun Watson, Aaron Rodgers) to Kyle Shanahan's eventual selection of Trey Lance with the high-cost, No. 3 draft pick. Then came the losses, another injury and intense criticism.

Garoppolo, however, will make his 39th start Sunday, four years to the day he got traded to the 49ers and on the same backyard lot, Soldier Field, as where he won his 49ers' starting debut in December 2017.

As his 49ers' tenure comes full circle, neither he nor Shanahan is indicating this is also where their marriage ends. No one can say for sure, though.

Asked Friday if a second straight bad game could cost Garoppolo his job, Shanahan said, "I would never answer a question like that. And you guys can ask it a thousand different ways, I don't think like that."

Instead, good or bad, he'll review the film and "you try to make decisions by Wednesday," which isn't exactly a vote of long-term confidence, nor is one expected after Shanahan acknowledged this last Wednesday acknowledging it's "a matter of time" before Lance ascends the throne.

So, hypotheticals rule the day. Speaking of, if Garoppolo didn't arrive in a Halloween 2018 trade, would Shanahan still be the 49ers' coach? If the 2019 49ers didn't blow a Super Bowl lead, would a dynasty be afoot rather than an expiration date upcoming on Garoppolo's tenure?

Here are the answers as to what must go right Sunday for the 49ers to improve to 27-12 in Garoppolo's starts:

LEADERSHIP POWER

Losing streaks invite speculation about a leadership void, and defensive end Nick Bosa isn't disputing that possibility.

"We're missing (George) Kittle out there with his vocal leadership, and Raheem (Mostert) was a really good vocal leader. Trent (Williams) is another vocal guy," Bosa said Thursday.

"So it does help to have some guys more vocal and will get on other guys about certain things. But we have to work with what we got and we definitely have enough leaders out there that we should be able to do our job, on offense and defense."

The 49ers have lacked explosive plays in all three phases this season. Deebo Samuel has been a one-man band on offense, and Bosa his equal on defense.

Neither Samuel nor Bosa is a team captain. That title, instead, is shared by Kittle, Williams, Mostert, Arik Armstead, Jimmie Ward, Fred Warner and Garoppolo.

AVOID DEFENSIVE PENALTIES

The 49ers' pass defense has been vulnerable all season to deep passes, and the Indianapolis Colts seized on that last game: defensive backs drew five pass-interference penalties (three accepted, 97 yards).

So, when it comes to a scouting report for the 49ers' defense, it's come to this:

— The Bears have drawn a defensive pass interference penalty on their opponent in 5 of 7 games.

— Allen Robinson was targeted on three of those PI calls, and former 49ers receiver Marquise Goodwin on the other two. "Alan Robinson has always been really good at getting DPIs against him," Bears coach Matt Nagy said Friday.

— Land Clark, Sunday's referee, has called only four DPI penalties over six games this season.

— The 49ers can not, should not, must not add to their NFL-high total of 14 DPI penalties, including five from Sunday night's atrocious outing that fueled a 30-18 home loss to the Colts.

"It's way too bad right now," Shanahan said. "No matter what the situation is, it's tough to win games if you don't fix that."

THIRD-DOWN IMPROVEMENT

The 49ers' third-down offense bottomed out last game, converting on only 1-of-11 attempts and sabotaging series after series against the Colts, just like they did in preceding losses to Seattle (2-of-14) and Arizona (3-of-14).

Three of the 49ers' four turnovers last Sunday came on third down, starting with fumbles by Deebo Samuel and Garoppolo before a fourth-quarter interception on a Garoppolo pass to Samuel.

"Being 1-for on third downs doesn't go away," offensive coordinator Mike McDaniel said. "You're thinking about it in bed, you're thinking about it all the time."

Think about this inefficiency on third-down runs: 0-for-8 on any carries beyond third-and-1, not counting third-and-7 scrambles.

Think about this inefficiency on third-down passes: 0-for-11 on passes longer than third-and-10, and just 6-for-24 on third-down passes needing at least 8 yards.

STREET BALL

Defensive tackle Kentavius Street drew the nickname "Baby Hulk" for his prodigious strength upon joining the 49ers, albeit as a medical redshirt because of a torn ACL prior to the 2018 draft. The 49ers need him more than ever to act like a superhero.

With Javon Kinlaw (knee) and Maurice Hurst (calf) out, the 49ers want Street to complement a defensive front that will be attacking rookie quarterback Justin Fields. He, D.J. Jones and perhaps Arik Armstead must pressure the pocket from the interior.

Street got credited with a fumble-forcing sack last game, even though Nick Bosa also had a grasp of Carson Wentz on a pitch into Azeez Al-Shaair's hands.

"Everybody in this building has known he can do that for a while, physically how gifted he is," Bosa said of Street. "He's a great guy and has worked hard, and he hasn't really gotten a hang of it until recently. He's playing really well and has to keep it up."

RUNNING TO VICTORY

Both teams, with shaky offenses, will look to thrive first on the ground.

For the 49ers, Elijah Mitchell is coming off the second 100-yard game of his rookie season, and team officials not only covet his speed but his ball security. Meanwhile, JaMycal Hasty didn't fare so well as a third-down back last game, and Trey Sermon didn't get a chance, at all.

"We've got to utilize those guys because that makes our offense go. It always has," general manager John Lynch told KNBR 680-AM.

Lynch envisioned "explosiove runs" in Mitchell's future. But he also expects Sermon, his third-round pick, to get summoned off the bench eventually as a rookie.

The Bears can't protect Fields, so their best shot is to attack a 49ers run defense that just allowed its first 100-yard rusher since 2019. Rookie Khalil Herbert has become a fantasy-football favorite with his three-game production (272 yards) since replacing the injured David Montgomery and Damien Williams.

Linebacker Fred Warner echoed Shanahan's contention this week that "star players have got to be star players," without necessarily overachieving.

"There's not some magic potion or drink or an assignment to go make a pick-six to win the game," Warner said. "I'll go out and do my assignment to the best of my ability as hard as I can go."