The acquisition of outside linebacker Khalil Mack inspired many to compare the Bears’ defense to coordinator Vic Fangio’s top-notch 49ers defenses.

Mack can be outside linebacker Aldon Smith, the fearsome pass rusher off the edges.

Akiem Hicks is a younger, bigger version of Justin Smith, an immovable object up front.

And Roquan Smith is the second coming of Patrick Willis, the tackling machine in the middle of everything.

But what about the safeties?

When the 49ers appeared in three consecutive NFC Championship Games (2011-13), Fangio’s defenses ranked among the top five in the NFL in yards and points allowed each season. They had Pro Bowl-caliber players at every level, including at safety, with Dashon Goldson (2011-12), Donte Whitner (2012) and Eric Reid (2013). Goldson was named a first-team All-Pro in 2012.

Mack’s arrival benefits every member of the Bears’ defense. As Fangio said, the Bears are looking for a ‘‘chain reaction’’ and a ‘‘domino effect.’’ But Mack also is a great player who leads to greater expectations for all.

As the Bears’ last line defense, it’s time for safeties Adrian Amos and Eddie Jackson to do more — and they know it.

If the Bears are going to follow the 49ers’ model, Fangio needs better ball production from his safeties. In 2011-13, the 49ers’ starting safeties accounted for 18 interceptions and 62 pass breakups during the regular season, according to Pro Football Reference.

‘‘Let’s get it flowing now,’’ Jackson said. ‘‘We’ve got a year under our belt together, so let’s go ahead and take it to another level for Year 2.’’

That apparently has happened already when it comes to assignments and communication. Amos and Jackson said Fangio and secondary coach Ed Donatell trust them to make the proper adjustments without much, if any, consultation with them.

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‘‘If we see something on the field, we can adjust to it ourselves without having to go ask coach Ed,’’ Jackson said. ‘‘As long as we’re on the same page, we’re good.’’

It extends to certain matchups on the field, too. How that plays out Sunday against the Packers, though, remains to be seen.

‘‘We both want to be in the mix in certain situations,’’ Amos said. ‘‘It’s good that we practice both assignments and every coverage, so that any given time, against whoever we’re playing, we can be multiple in that.”

Jackson said things clicked for the two during the offseason program and in training camp.

‘‘Last year, we were building to it at the end of the season,’’ Jackson said. ‘‘I was a rookie and still growing and still earning trust from these guys.’’

Jackson has it now. He answered questions about his tackling ability over 16 starts and displayed game-changing ability with two return touchdowns against the Panthers.

‘‘It’s like a thunder-and-lightning combo,’’ Jackson said. ‘‘[Amos is] the hitter. He’s the thunder; I’m the lightning. It’s fun, man. We can keep offenses off-balance. And both of us can do some things with the ball in our hands. I love [playing with Amos].’’

The Bears would love to see the ball in Amos’ hands more. As Pro Football Focus’ lofty analysis of Amos points out, he’s a reliable defender who does many of the little things correctly. But his 90-yard pick-six of Ravens quarterback Joe Flacco last season still is his only interception in 40 career starts.

‘‘We want him to play well so our team wins,’’ Donatell said when asked during camp about PFF’s high grade of Amos. ‘‘We didn’t win enough games last year.’’

With the Bears’ entire starting secondary returning, that might change this season. But if the Bears are going to do what the 49ers

did, Amos and Jackson have to be better.

‘‘We know what to expect from one another,’’ Amos said. ‘‘We know what each other likes to do. There is no back-and-forth about what we’re doing. We just know.’’