FORT MYERS, Fla. — A curiosity has loomed ever since the Red Sox and Padres consummated the blockbuster deal that brought Adrian Gonzalez to Boston in December. Why did the Sox sacrifice three of their top prospects this winter rather than waiting until after the 2011 season to target the star first baseman as a free agent?

After all, the prospect haul given up by the Sox was formidable. Pitcher Casey Kelly, first baseman Anthony Rizzo and center fielder Rey Fuentes all project as potential impact contributors down the road. Under general manager Theo Epstein, the Sox had never given up that kind of prospect package for a player.

So why did the team make its play for Gonzalez when it could have simply waited a year and then chased him as a free agent while keeping its full complement of prospects? A reminder of the answer to that question was offered on Tuesday.

Gonzalez’ agents, John Boggs and Tony Cabral, met with Epstein and Sox assistant GM Ben Cherington on Tuesday to resume the negotiations that took place prior to the completion of the trade between the Sox and Padres in December. Afterward, Boggs made clear that the team and player remain on the same page in their efforts to get a long-term extension done — expected to be in the seven-year, $154 million range for the 2012-18 seasons — that both sides consider palatable.

“I would anticipate something [getting done] around April. When in April, I don’t know. It could be beginning, middle, end, but that’s it. That’s really the parameters we’re looking at,” Boggs said after the meeting. “I would be unpleasantly surprised if everything didn’t go in a positive direction. I think this was just an expansion on that. It could have been a lot different if we’d walked out of this thing and gone, ‘Man, those weren’t the people that we left in December in Boston. Are you kidding me?’ It wasn’t that at all. We’re pretty much on the same page.”

Boggs also reiterated that Gonzalez is seeking the same contract parameters discussed in December. He is not concerned with how the market landscape could shift based on what happens with first basemen Albert Pujols and Prince Fielder (both, like Gonzalez, eligible for free agency following the 2011 season).

“Adrian in his mind, he knew what it was going to take, bottom line. He wasn’t concerned with chasing after or breaking records. He just wants to be fairly compensated,” Boggs said. “Yes, you think that you’re giving away something that might or might not happen. In the end, I think he’s said it the clearest, you can be very wealthy and play for a team that you don’t want to play for or you can be very wealthy and play for a team that you want to play for and is in competition every year.

“That’s really what his goal was,” Boggs added. “To be treated fairly and be compensated fairly and be on a ballclub that is year after year competitive. I think that was his goal and after that, if he feels that it’s fair financially, he’s good to go.”

That approach — in which Gonzalez was willing to stick to a defined set of negotiating parameters, and wait until after he had demonstrated the health of his shoulder before signing a contract extension — was a critical component of the Sox’ desire to acquire the first baseman before he hit free agency. At the time of the trade — which was concluded just days before the landmark signing of Carl Crawford — the team remained skittish about the likelihood of landing a superstar free agent.

The Sox remained mindful of its failure to reel in Mark Teixeira when he was a free agent in 2008, and the memory of the failed negotiations to acquire Alex Rodriguez in 2003 also loomed.

The Sox have shown a willingness over the years to walk away from talks with free agents if demands surpass the team’s defined limit on the player’s value. That was the case in the talks with Johnny Damon, Teixeira and Rodriguez (though it is worth noting that the pursuit of Rodriguez was not a free agent scenario), among others.

Multiple team sources felt that the best chance to acquire Gonzalez — not just for the 2011 season, but also the long haul — was to acquire him in the December trade, thus giving them a more controlled negotiating environment than might exist in free agency.

Even assuming that the Yankees (who have Teixeira locked down at first for years to come) wouldn’t be involved in bidding for Gonzalez, Fielder or Pujols after the 2011 season, the Sox were still leery of the prospect that other teams could swoop in to drive up the market for Gonzalez. One need look no further than the stunning move by the Nationals to sign Jayson Werth to a seven-year, $126 million deal this winter to be reminded of the possibility.

More often than not, free agency erases precedent rather than respecting it, pushing salaries to surprising new peaks that exceed expectations entering an offseason. That being the case, the Sox envisioned a scenario in which they would have been priced out of a free agent market for Gonzalez, a player whose package of elite offense and defense they covet.

After all, though the opinion is far from unanimous, multiple executives of other teams have said this spring that, in theory, they would rather pursue Gonzalez over Pujols in free agency, given the respective ages and talents of the two players. So while the Sox are currently discussing an extension that would pay the first baseman $22 million a year, it was not difficult to envision that figure going up significantly — whether in years, dollars or both.

Moreover, there was the matter of Gonzalez’ bargain contract for the 2011 season. He’s receiving a mere $6.3 million in the option year of a deal he signed in 2007. That’s a good $15 million less than what his value would be for the year on the open market.

Put another way: If the Sox had waited until Gonzalez was a free agent after the season to pursue him, Teixeira’s eight-year, $180 million deal likely would have represented a negotiating baseline. In this case, the Sox appear likely to pay approximately $160 million (the $6.3 million option plus $154 million over the next seven years) for eight years. It does not seem a stretch to say that, in this context, they could be saving approximately $20 million on Gonzalez.

And that is before one factors in the potential savings that the club will achieve in terms of luxury tax thanks to the first baseman’s club-friendly deal for 2011. Because Gonzalez is willing to wait until after the start of the season to sign his extension — thus meaning that the extension will not be factored into 2011 team payroll calculations — the team will save more than $4 million in luxury tax payments for the coming year.

Finally, there was significant value to the Sox in acquiring Gonzalez and getting a long-term deal now rather than waiting another year based on projected performance.

As it stands, the first baseman will be delivering what should be one of his prime seasons to the Sox as a 29-year-old in 2011. Assuming that he signs a seven-year extension, he will be under contract from ages 29-36. Had the team waited to chase Gonzalez as a free agent, it might have still been looking at an eight-year deal, but such a pact would have covered Gonzalez’ age 30-37 seasons.

In other words, the Sox are getting an incredible bargain for a year of Gonzalez’ prime (age 29) rather than paying full free agent value for a season in which he would likely be showing decline (age 37).

Gonzalez was the player the Sox wanted. They are getting him when they want him, both in terms of their competitive ambitions for the 2011 season and in terms of the first baseman’s age and career stage. And by acquiring him this past winter, rather than waiting until he was a free agent, the team is realizing savings (between his contract and the luxury tax) that could easily exceed $25 million.

All of those factors were at play when the Sox swallowed hard and made the decision to pull the trigger on parting with a tremendously talented group of prospects. Under typical circumstances, the Sox would not have been inclined to make such a deal. But in the end, Gonzalez’ availability and negotiating stance represented an extraordinary occurrence that led the Sox to make their deal.