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Aaron Gleeman writes for HardballTalk at NBCSports.com, serves as senior editor at Rotoworld, and blogs about the Twins and Mila Kunis at AaronGleeman.com. He once saw Jay Jaffe's mustache in person and it changed his life.

Four years and one week ago, the Twins and Mets completed a blockbuster trade that sent Johan Santana to New York for prospects Carlos Gomez, Deolis Guerra, Kevin Mulvey, and Philip Humber. Santana, who'd won two Cy Young awards during the previous four seasons and deserved a third trophy that was misguidedly given to Bartolo Colon, signed a six-year, $137.5 million contract extension as part of the deal.

Santana was baseball’s best pitcher entering his age-29 season, and the Twins were consistent contenders with four division titles in the previous six seasons. However, for months it had been clear that they were unwilling or unable to keep their ace, who had one year and $13.25 million remaining on his contract, in Minnesota long term. Even letting him play out the season before recouping draft picks from his free agent departure never seemed to be an option.

Instead, the Twins spent all offseason shopping their ace, with the Yankees, Red Sox, and Mets emerging from the drawn-out negotiations as the three legitimate suitors. That those three teams wanted the best pitcher in baseball was no surprise, but each of them also had the well-stocked farm systems to put together strong offers and, perhaps most importantly, the financial means to give Santana the massive long-term deal he required.

Twins fans who watched Santana’s remarkable development from Rule 5 pick to Cy Young winner certainly weren’t thrilled about that reality, particularly since new general manager Bill Smith would be making the franchise-altering decision just months after replacing Terry Ryan. However, the ability to drool over all the top-ranked prospects being mentioned as possible trade targets made things a little easier to take.

It was like being let loose for a shopping spree in the prospect store, or so Twins fans hoped. In the Red Sox aisle were Jacoby Ellsbury, Jon Lester, Clay Buchholz, Justin Masterson, and Jed Lowrie. In the Yankees department were Joba Chamberlain, Phil Hughes, Melky Cabrera, Ian Kennedy, and Austin Jackson. And in the Mets section were Fernando Martinez, Carlos Gomez, Deolis Guerra, Jon Niese, and Kevin Mulvey.

At various points, each of the three teams was said to be the “favorite” to land Santana, and speculation swirled for months around some of the best young players in baseball. For instance, Nick Cafardo of the Boston Globe reported on December 23 that the Red Sox had offered Lester, Masterson, Lowrie, and Coco Crisp, while Charley Walters of the St. Paul Pioneer Press reported that the Twins were holding out for Ellsbury.

Joe Christensen of the Minneapolis Star Tribune reported on January 10 that the Twins had asked the Mets for Martinez and Gomez, along with multiple pitching prospects, but New York was hesitant to include both outfielders. Mike Puma and Mark Hale of the New York Post reported on January 15 that the Twins asked the Yankees for Hughes, Cabrera, Kennedy, and Jeff Marquez. And those are just a fraction of what were constant rumors.

Yet as spring training neared, there were reports that the Red Sox and Yankees weren’t quite as interested in breaking the bank for Santana as initially expected, in terms of both money and prospects. Then, as speculation shifted to the Mets as front-runners for Santana, they were said to be balking at including Martinez, who at the time was a 19-year-old center fielder and their consensus top prospect.

Ultimately, the Twins left that supposed shopping spree with a half-filled cart and a lot of confused fans. Not only couldn’t they pry Ellsbury, Masterson, and Lester from the Red Sox or Hughes and Cabrera from the Yankees, they couldn’t even get the Mets to include Martinez. All those juicy rumors and all those exciting scenarios played out over months resulted in trading baseball’s top pitcher for Gomez, Guerra, Mulvey, and Humber.

Perhaps the offseason-long buildup had raised expectations to the point that any kind of realistic return for Santana would have been disappointing, because while they paled in comparison to the packages Minnesotans had been dreaming on, those four prospects were still plenty valuable. In fact, Baseball Prospectus’ own Kevin Goldstein spoke to a Mets official who described the Twins as having “ripped the heart” out of their farm system with the deal.

Goldstein ranked Gomez and Guerra as his No. 65 and No. 79 prospects, respectively. Baseball America was even higher on them, ranking Guerra at No. 35 and Gomez at No. 52. Humber had taken a step backward after ranking No. 73 on Baseball America’s list the previous year, but the former third overall pick still had mid-rotation starter upside at age 25, and Mulvey, a 23-year-old former second-round pick, had similar potential.

Minnesota had failed to get an elite prospect for Santana, but two top-100 prospects and two other quality minor leaguers certainly wasn’t a disastrous return. Of course, most Twins fans were still very disappointed by a package built around Guerra and Gomez instead of Ellsbury and Lester or Hughes and Cabrera, and most Mets fans were thrilled to land an in-his-prime ace without surrendering Martinez.

Four years later, it turns out no one should have been happy.

Initially, though, it looked like a blowout victory for the Mets. Santana was his usual brilliant self in 2008, throwing a league-leading 234.1 innings with a league-best 2.53 ERA. Meanwhile, the Twins rushed Gomez to the majors as their Opening Day center fielder, replacing Torii Hunter, and he hit just .258/.296/.360 with a 142/25 K/BB ratio in 153 games while looking anything but MLB-ready at age 22.

Guerra got knocked around at High-A as a 19-year-old, posting a 5.47 ERA with as many walks (71) as strikeouts (71) in 130 innings, and was nowhere to be found on top-100 prospect lists the next season. Humber and Mulvey spent the year as Triple-A teammates, and neither pitched particularly well, although Humber at least saw some September action as a mop-up man in Minnesota.

Santana continued to pitch very well in 2009, making the All-Star team and posting a 3.13 ERA, but he was limited to just 25 starts and spent the final six weeks of the season on the disabled list following surgery to remove bone chips from his elbow. Meanwhile, the Twins tired of Gomez’s hacktastic ways and total lack of progress, benching him for Denard Span and then trading him to the Brewers for J.J. Hardy that winter.

Guerra again struggled in the minors, posting a 4.89 ERA with just 106 strikeouts in 149 innings between High-A and Double-A as a 20-year-old who had no business that far up the organizational ladder. Mulvey repeated Triple-A with similarly underwhelming results and was traded to Arizona for reliever Jon Rauch in late August. Humber also repeated Triple-A and was so unimpressive that the Twins let him leave as a free agent.

Santana returned from 2009 elbow surgery with a 2.98 ERA in 2010, but his strikeout rate fell to a career-low 6.5 per nine innings, his average fastball clocked in at 89 miles per hour, and in September he had rotator cuff surgery. He hasn’t pitched since, missing all of last year, and may not be ready to begin 2012. He made $22.5 million without throwing a pitch in 2011, and the Mets still owe Santana, now 33, another $55 million for 2012 and 2013.

Guerra is the lone piece of the original Santana package still in Minnesota’s organization, but instead of developing into a top-of-the-rotation starter, he’s 23 years old with a 4.95 career ERA in the minors and is now hoping to reach the big leagues for the first time as a reliever. Gomez hasn’t put his physical tools to good use in Milwaukee either, and Mulvey has spent four straight seasons at Triple-A with a 4.45 ERA to show for it.

Against all odds, Humber now looks like the most valuable player from Minnesota’s haul, although he hasn’t done the Twins any good. He was picked up and let go by the Royals and A’s but finally stuck in the majors with the White Sox last season and threw 163 innings with a 3.75 ERA at age 28. Rauch left the Twins as a free agent after one-and-a-half solid years, and Hardy had an excellent 2011 only after being dumped on the Orioles.

There's a tendency to declare an immediate “winner” in every trade, and even when taking a long-term view of a blockbuster deal involving a superstar in his prime being swapped for a multi-prospect package, it's usually fairly easy to determine who benefited most. When it comes to this trade, however, the question is more like who suffered least. And even that’s tough to say, because everyone involved went bust.

Four years into their six-year, $137.5 million investment in Santana, the Mets have gotten just 88 starts of ace-caliber pitching and an uncertain future. And for their in-his-prime ace, the Twins ended up with 1.5 seasons of a replacement-level Gomez and a year of Hardy that they later squandered, 1.5 seasons of Rauch by way of Mulvey, nothing from Humber, and whatever hope still remains that Guerra can turn into a useful reliever.

Remarkably, it wouldn’t have turned out any better if the Mets had given in to the Twins’ request for Martinez, whose arthritic knees and lack of development while being rushed through the minors resulted in his being placed on waivers last month. Houston used its No. 1 waiver priority to snag him directly in front of Minnesota, but Martinez is now a gimpy 23-year-old corner outfielder who slugged .417 at Triple-A last season.

No matter which prospects Minnesota asked for and which prospects New York agreed to part with for Santana, any trade with the Mets was essentially destined to be a failure for the Twins. Many of their reported Red Sox and Yankees targets went on to become impact players, but even if the Twins could have talked them into upping the ante, there were plenty of landmines among those future stars.

In retrospect, the Twins would have benefited most by trading with the Red Sox. Ellsbury and Lester have excelled in Boston, Buchholz has at times been on the verge of the same, Masterson became a borderline ace after being traded to the Indians for Victor Martinez in mid-2009, and even Lowrie has been useful despite a lengthy injury history. Any package of Red Sox would have dwarfed the Mets’ return.

Yankees prospects linked to Santana have been more of a mixed bag. Chamberlain and Hughes have both seen their careers derailed by injuries, and Cabrera, despite a very good 2011 season, has been little more than a decent regular. Kennedy turned into an impact starter, but only after struggling through injuries and a trade to the Diamondbacks, and Jackson has so far been just a rich man’s Gomez after being traded to the Tigers.

Months of headline-grabbing rumors about baseball’s best pitcher being shopped for an assortment of baseball’s best prospects, leading to a blockbuster trade and a $137.5 million contract extension. And four years later, the general managers who pulled off the swap, Smith and Omar Minaya, have both been fired, and Mets fans and Twins fans could argue all day about which team got the worse end. At least it made for an interesting winter.