Adam Schefter explains how the Packers' additions of DE Za'Darius Smith, DE Preston Smith and DB Adrian Amos is a full makeover of the defense. (0:58)

GREEN BAY, Wis. -- When word began to circulate a few weeks ago at the NFL combine that the Green Bay Packers would be big players in free agency, it was met with plenty of "yeah, right" responses.

And when the first day of the negotiating period passed with no action, the "yeah, right" crowd could have argued that these were the same old Packers who never did much in the opening rush of free agency under former general manager Ted Thompson.

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Then came Tuesday morning.

Before lunchtime, second-year GM Brian Gutekunst landed four free agents who had agreed to contract terms: pass-rushers Za’Darius Smith (formerly of the Ravens) and Preston Smith (Redskins) plus safety Adrian Amos (Bears) and offensive lineman Billy Turner (Broncos).

So why did Gutekunst go all-in the day before the league year opened?

"He had to do something," a league source said Tuesday.

Here’s why:

The Packers’ 2015 draft class, one he inherited from Thompson (although he played a part in it then as director of college scouting), had almost nothing left. That class was the one that hits the unrestricted free-agent market this year, and the only player left in Green Bay from that draft last season was linebacker Jake Ryan (fourth round). And Ryan spent the entire season on injured reserve after he blew out a knee in training camp and likely will only be re-signed for a bargain deal.

His defense was so badly in need of playmakers after he added only a couple of aging veterans (Muhammad Wilkerson and Tramon Williams) last year in free agency to help new coordinator Mike Pettine.

With plenty of needs on offense for new coach Matt LaFleur, he now can focus on that side of the ball with some of his top draft picks.

Only Gutekunst knows why he didn’t do this in his first year to help embattled former coach Mike McCarthy. Perhaps he overrated his returning roster, but he knows he has to give Pettine more than he had last year in his first season in charge of the Packers’ defense, a unit that miraculously finished 18th in the league rankings.

The Packers are counting on Za'Darius Smith, above, and Preston Smith to give them the edge rushers they have been missing. Nick Wass/AP Photo

Regardless of whether Gutekunst overpaid for Tuesday’s foursome or got the financials right, he can’t be accused of taking a passive approach, especially when it came to the pass-rushers. Gutekunst spent $36 million in signing-bonus money on the two Smiths -- $20 million for Za’Darius and $16 million for Preston, according to sources with access to the contract details.

They essentially replaced the pass-rush tandem of Clay Matthews and Nick Perry. Matthews will become a free agent Wednesday when the league year opens, and Perry was released on Tuesday before the Packers had to pay a $4.8 million roster bonus later in the week. Perry was due to make $11 million this season with a cap hit of more than $14 million, while Matthews made $11.4 million last season and had the same cap charge. The Smiths’ 2019 pay will be more, but their cap charges will be much lower.

And, according to one longtime NFL scout, they’re "better than Nick Perry and Clay as pass-rushers."

In two offseasons, Gutekunst has replenished perhaps the Packers’ two weakest positions on defense: cornerback last year with first-round pick Jaire Alexander and edge rusher this year with the Smiths. The cornerback position would be even more solid if the Packers re-sign pending free agent Bashaud Breeland.

This also opens up the possibilities for Gutekunst in the draft, where he has two first-round picks (Nos. 12 and 30) and three picks in the top 44 overall.

Had he failed to land pass-rush help in free agency, he would have been forced to use one -- or both -- of his first-round picks on an edge player.

It’s a deep draft on the defensive front, and now the possibilities are endless. He still could go with an edge rusher if one of the top players at the position is on the board when it’s his turn at Nos. 12 or 30, but he doesn’t have to if it’s a force fit.

LaFleur no doubt would like another running back to go with Aaron Jones, whose durability has been an issue, and Jamaal Williams, who isn’t as good a fit as Jones is for the outside zone runs that the new coach relies on. He also could use another offensive lineman or two who can fit that kind of blocking scheme. And there’s always room for more targets for quarterback Aaron Rodgers. It’s a strong tight end class, especially at the top, and even though Jimmy Graham is expected back for another year, that position remains a need, as does receiver, given that slot man Randall Cobb isn’t expected back.