SAN JOSE — The 49ers took down their “vacancy” sign from the free-safety hotel Saturday.

Craig Dahl, formerly of the St. Louis Rams, was signed to fill (as he put it) the “voided” position created when Dashon Goldson left as a free agent.

So was this a good thing? Yes. This was a good thing. Dahl, a good tackler and smart defender with six years of experience, will give the 49ers a solid presence at an important position.

But was it an earthshaking move? No. The vast majority of free-agent signings move no earth at all. But people get way too excited about them because … well, because the NFL has such a grasp on the sports public that if the league scheduled a “Burping Day” for potential draftees and put it on the league’s television network, thousands would tune in to watch offensive tackles line up and belch.

(The real NFL scouting combine in Indianapolis, by the way, is just about that riveting to watch.)

The same rule applies to the dance that began last week with veteran players who were eligible to negotiate deals elsewhere. It kicked off what I call the Free Agent Wild And Crazy Overhyped Blowout season — or for short, the FAWACOB.

The FAWACOB creates much minute-to-minute speculation and day-by-day player resettlement. It is promoted and amplified by the ever-churning social media. That’s fine and harmless fun. However, I fear that because of all the Twitter-update and did-you-see-whom-the-Seahawks-got-today fever, many fans miss the FAWACOB’s most helpful benefit:

It serves as a beautiful truth serum.

Here’s why: After all the blather about players and “how much they mean” to their teams over the previous few months, the FAWACOB forces every franchise to finally during come clean and tell you by their actions what they really think about their roster.

In the 49ers’ case, the release of Goldson — followed by a visit from free agent Charles Woodson that led to no contract, followed by a visit from Dahl that resulted in Saturday’s signing — tells us much.

You might ask why the 49ers, rather than put the franchise tag on Goldson to keep him around as they did last season, allowed him to walk away and eventually agree to a five-year deal for $41.25 million with Tampa Bay. You might wonder why the 49ers, in fact, never even made Goldson an offer to try to keep him.

Simple. It’s because they didn’t think Goldson was worth it. Worth the money. Or worth the trouble.

Harsh words? Of course. But the NFL is not a sensitivity-training organization.

My belief is that the 49ers recognized that Goldson might not fit into the transforming landscape of the NFL, especially as it relates to dangerous contact.

Goldson was a very good safety. He made two Pro Bowl rosters. He was a fairly impressive ballhawk who could play center field against deep passes — although Goldson’s three interceptions in 2012 were half the number he snatched in 2011 and he (along with the rest of the 49ers secondary) seemed to struggle in the playoffs.

Goldson’s most vaunted asset, though, was that he hit hard and could blow up receivers or runners. The problem is, Goldson went over the edge with those hits more than any other 49er. He led the team in unnecessary roughness penalties (four) and unsportsmanlike conduct calls (two). He was fined three times by the NFL last season, including a $21,000 penalty for a helmet-to-helmet hit against New England. The other two fines were for one of those unnecessary roughness calls and a taunting display.

The 49ers won’t come out and say outright that they didn’t want that sort of player. But in Saturday’s news release about Dahl’s signing, general manager Trent Baalke referred to his new safety as “an experienced veteran with excellent intangibles.”

Read between the lines. For the record, Dahl accumulated five total penalties with the Rams last season. Only one was of the personal-foul nature, for a horse-collar tackle. Dahl might not be as good at snarfing up interceptions (he has only four in his career), but he isn’t going to bring out flags for excessive violence.

Keep in mind that rules about such violations will become stricter, not more lenient, in the future, especially as the class-action concussion lawsuit by former players against the NFL moves through the system.

Dahl was asked Saturday about all of that — not as a comparison with Goldson’s technique, just as a general subject — and noted that the safety position “is evolving” in many ways.

“I think a conscious effort has been made by players to change their style of play,” Dahl said. “Instead of leading with your head, you lower your target that you’re aiming at while tackling.”

Dahl, in his conference call, also said the 49ers told him they wanted to find a player who could “fit their mold.”

Hmmmm. Interesting. One player apparently fit the 49ers mold. Another didn’t. The same principle surely applied when Randy Moss was not offered a new deal by the 49ers — but another wide receiver, Anquan Boldin, was aggressively pursued and acquired via trade. All those words about Moss’ astounding value to the team as a mentor in 2012 meant nothing. The actions spoke far louder. The same principle, in fact, applies in a certain extent to every signing by every team in the past week.

The FAWACOB might be overrated as a difference-making exercise, because so few free agents truly alter the NFL landscape. But as a truth serum, the FAWACOB is unmatched.

Contact Mark Purdy at mpurdy@mercurynews.com. Follow him on Twitter at twitter.com/MercPurdy.