In the first days of the NFL’s free-agency period, the Raiders have spent and the 49ers have slept.

Oakland has opened its overstuffed wallet to secure a road-grading offensive lineman (Kelechi Osemele), an elite edge rusher (Bruce Irvin) and a top cornerback (Sean Smith) for $43.9 million in guaranteed money.

The 49ers? Despite also being flush with cash, they’ve signed journeyman quarterback Thad Lewis and are known to have hosted two other who’s-he players, Ted Larsen and Lance Dunbar, on free-agent visits.

What’s going on here?

For starters, it should be noted that few teams outside of last year’s Broncos spend their way to Super Bowls. It’s widely considered prudent to build through the draft and judiciously supplement with free agents (see Packers, Patriots, Ravens).

Still, the early stages of free agency have solidified a belief that began taking hold last year: The Raiders — yes, the Raiders of the Lost Stadium — are headed in a better direction than the 49ers.

In 2015, the Raiders took significant steps under first-year head coach Jack Del Rio and the rising-star trio of quarterback Derek Carr, rookie wide receiver Amari Cooper and linebacker Khalil Mack. Meanwhile, the 49ers kept regressing under since-fired rookie head coach Jim Tomsula and disgruntled and demoted quarterback Colin Kaepernick.

Now, it has come to this: Smith, who was being courted by the 49ers, chose to sign with the Raiders, and no observers argued with his logic.

“I just felt like with a few more pieces,” Smith said, “this team is ready to contend for real.”

So is there truth to the popular story line that the Raiders have become a destination and the 49ers are now a disaster?

That the Raiders are a destination is funny in itself, as they don’t know where they are going to be playing after next season. Whether they wind up in Los Angeles or San Diego (if the Chargers leave) or by some miracle, something gets done in Oakland, one thing is clear:

Owner Mark Davis wants to win now.

And after back-to-back home run drafts by general manager Reggie McKenzie and the hiring of Del Rio, whose leadership galvanized players last season, the Raiders are in a position to do so.

All they needed to do was take their $60 million-plus in salary-cap space and address some critical needs in free agency. Maybe a bully offensive lineman, a pass rusher to complement Mack and their first true No. 1 cornerback since Nnamdi Asomugha left.

Check, check, check. (In more ways than one.)

And unlike previous years in which McKenzie’s hands were tied because of a lack of money or a lack of a desirable team, all the players are under 29 years old. No more overpaying players who didn’t have better options in order to show Oakland’s younger players how to win. School is over. Go win, baby.

Osemele had back surgery in 2013 but played well last year, and the team thinks he can be an impact player at guard or tackle. Irvin didn’t become the next Aldon Smith as the Seahawks had planned, but he has shown he can get to the quarterback, and is a favorite of defensive coordinator Ken Norton Jr.

Smith is exactly the big, physical cornerback (6-foot-2, 215 pounds) that the defense of Norton and Del Rio needs.

And the Raiders aren’t done yet. They have $28 million in salary-cap space and need a safety, inside linebacker, another offensive lineman and running back. With another signing or two in the next week, they can take the best player available at No. 14 in next month’s draft.

Oakland is one of four teams in on former San Diego Pro Bowl safety Eric Weddle, who plans to look at initial contract offers and take the weekend to consider where he visits first. It’s also in on former Jets and Vikings linebacker Erin Henderson, and there is a still a small chance it can re-sign left tackle Donald Penn.

There is a real sense that the playoffs are the next step after last season’s 7-9 record.

The 49ers, of course, finished 5-11, but pointed to legitimate reasons for optimism in January.

CEO Jed York noted the team’s salary-cap space ($53.7 million) and slew of draft picks as he expressed confidence in general manager Trent Baalke’s ability to rebuild.

Two weeks later, it was clear the 49ers had made their assets a selling point with Kelly, who sounded ready to start reshaping the roster.

“You look at where they are in relationship to the salary cap,” Kelly said. “You look at where they are in terms of having 21 draft picks over the next two years. ... They’re prepared for the future, and it’s an exciting time to be part of that.”

However, few teams have been duller in the early stages of free agency. The 49ers have committed at least $5 million annually to bring back their top in-house free agent, nose tackle Ian Williams, on a five-year deal. In addition, they re-signed placekicker Phil Dawson on a one-year deal reportedly worth $3.1 million.

But their overall lack of activity has created a confused chorus: What the heck are they doing?

It’s possible they are simply refusing to budge from their measured approach to free agency, regardless of their healthy bank account and thin roster.

Baalke no doubt rolled his eyes in recent days as other teams doled out mega money for marginal players. The Falcons, for example, signed wideout Mohamed Sanu to a five-year, $32.5 million deal after his 33-catch performance in 2015.

“You can’t just spend money to spend money,” York said in January. “You want to make sure that you’re spending money wisely.”

The 49ers could be surveying the free-agent landscape and concluding that the best way to start rebuilding is by focusing on their 12 draft picks. It’s a significant bounty that could include another second- or third-round pick if, as expected, they trade Kaepernick.

A more sobering possibility for fans? The 49ers are ready to spend, but players are unwilling to accept their cash, given the state of a franchise increasingly marked by anonymous-source-fueled dysfunction. Last year, puzzled wide receiver Torrey Smith, who signed with the 49ers in 2015, said he hadn’t experienced leaks to the media during his first four seasons with the Ravens.

And there is the matter of Kelly, who repeatedly waas ripped by ex-players during his three seasons in Philadelphia. It’s possible some of that was sour grapes, but public carping from prominent ex-Eagles such as DeSean Jackson and LeSean McCoy could make others wary of playing for Kelly.

In addition, free agents with options also might be leery of playing for a coach known for his devotion to sports science (daily urine tests) and frenetic-paced offense (running, running and running).

For his part, Baalke might find this situation familiar. In 2011, after the 49ers were coming off a 6-10 season, fans were up in arms as the team sat out the first days of free agency. After the market settled, however, Baalke made sales-rack signings that included Donte Whitner, Jonathan Goodwin and Carlos Rogers, three players who figured prominently in the franchise’s turnaround.

Five years later, however, the only NFL turnaround that looks imminent in the Bay Area involves the Raiders.

Their owner obviously wants to win now and, after his string of free-agent signings, it appears he could get what he paid for.

Eric Branch and Vic Tafur are San Francisco Chronicle staff writers. Email: ebranch@sfchronicle.com, vtafur@sfchronicle.com Twitter: @Eric_Branch, @VicTafur