One NFL fact of life Bill Polian said he learned during his time running the Indianapolis Colts from 1998 to 2011: The outside fascination with free agency is almost always greater than the payoff.

“Fans want you to go out and play fantasy football now,” Polian, an analyst with ESPN, said this week. “But that’s the last thing you should be doing. That money, if you miss, is gone and never comes back.”

Polian says the Seahawks have generally been able to successfully restrict themselves in free agency to filling specific needs while focusing on building from within.

“I think they do a great job of recognizing the fits,’’ Polian said. “Who fits for them, what specific role that guy will play. And then they do a good job of allocating their money.

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“And that’s what you have to do in free agency. That’s the blueprint for success in free agency, recognizing where the player fits, what he will do, does he fit your system, can he make a relatively seamless transition. And then making sure the money is right.’’

As another free-agency period begins this weekend, Polian is among those who expect the Seahawks to again concentrate on using free agency to fill a few needs while trying to keep its roster as intact as possible.

The free-agency period gets under way at 9 a.m. Saturday, when teams can begin negotiations with unrestricted free agents (though in another accepted NFL fact of life, talks have already been going on behind the scenes). Teams can sign players to contracts beginning at 1 p.m. Tuesday.

Seattle has 15 players who will be unrestricted free agents, highlighted by defensive lineman Michael Bennett and receiver Golden Tate. Other key players entering free agency include cornerback Walter Thurmond, defensive linemen Clinton McDonald and Tony McDaniel, offensive linemen Breno Giacomini and Paul McQuistan, and kicker Steven Hauschka.

Seattle, like all teams, found out last week it will have a little more money to work with when the salary cap for 2014 was set at $133 million (it was $123 million in 2013).

Combined with the release last week of high-salaried veterans Sidney Rice and Red Bryant, the Seahawks are roughly $18 million under the cap.

The rise in the cap, though, also means other teams have more money, which theoretically will create a better market for the most attractive free agents.

“History tells you there will be more deals out there for big money than there were last year,’’ Polian said.

That could make it particularly challenging to keep Bennett, who last year made $5 million on a one-year deal but is regarded now as one of the top defensive linemen available and will command much more.

Bennett will test the free-agent market rather than sign early with the Seahawks. That doesn’t mean he won’t re-sign with Seattle, just that he wants to see what other offers are out there first. Some think Bennett, whose agent is Drew Rosenhaus, could be seeking around $10 million per year and a long-term deal.

Tate is a harder read. He said last week he does not see himself as similar to Philadelphia’s Riley Cooper, who recently signed a five-year deal worth an estimated $4.5 million a year, indicating he expects a bigger deal. Some expect Tate might want as much as $6 million per season (he made a reported $880,000 in 2013).

Tate is considered one of the top receivers available and could receive tempting offers.

Receiver Doug Baldwin is a restricted free agent, meaning other teams can make him offers but Seattle would have the chance to keep him by matching. The Seahawks recently tagged Baldwin with a second-round tender. If Baldwin signs the tender offer, he would receive $2.187 million for next season. If Baldwin were to sign with another team instead, Seattle would be compensated with a second-round pick. Baldwin is looking for a longer-term deal with the Seahawks. (The team’s two other restricted free agents, offensive lineman Lemuel Jeanpierre and safety Jeron Johnson, signed tenders and are under contract for one more year.)

The receivers group available in the NFL draft is deep, and the Seahawks could let Tate go and assume they can get cheaper replacements in free agency or the draft.

And while the attention on Seattle’s free agents inevitably falls on the big names of Bennett and Tate, keeping — or replacing the production of — McDaniel, McDonald, Thurmond and Hauschka will be important.

Seattle, though, also has to balance what it spends now with what it knows it will have to spend later to retain some of its core players whose contracts will need extending in the next year or so, specifically safety Earl Thomas, cornerback Richard Sherman and quarterback Russell Wilson.

Seattle has been rumored ready to extend Thomas before the 2014 season and likely to try to get Sherman and Wilson done before 2015 (which is the earliest the Seahawks can give Wilson an extension).

Still, Seattle figures to explore free agency, particularly on the defensive line if it loses a few of its players, and at tight end.

Mostly, though, Polian says Seattle’s task is to navigate free agency while retaining the ability to keep its core together.

“Keep in mind, the best players are not in free agency,” he said. “They are already tagged (given a franchise or transition tag) or signed. … These are essentially B players whose agents are looking for A money.’’

Bob Condotta: 206-515-5699

or bcondotta@seattletimes.com. On Twitter @bcondotta