The Seattle Mariners have agreed to terms with Robinson Cano on a 10-year, $240 million contract, marking the most dramatic example to date of a franchise taking the $26 million per team per year in new national TV money and actually spending it. It’s a good deal for Cano and a potentially great one for the Mariners.

That new TV deal, announced 14 months ago, granted broadcast rights to Fox and TBS through 2021. Combine that with the league’s existing ESPN deal, and teams now stand to earn $12.4 billion over the lifetime of the contracts, more than doubling previous totals. Last winter and so far this winter, we hadn’t seen many teams that lack the big media-market power of L.A. or New York or Boston spending top dollar to land marquee players. The closest we’d come was Minnesota signing right-handed starters Ricky Nolasco and Phil Hughes in rapid succession to contracts worth a combined $73 million. This free-agent class, like last year’s, is short on superstars, but it still felt odd that the small- and medium-market clubs that had suddenly received a huge windfall of cash seemed content to stick the money under their mattresses, rather than spending it on good players who could help win games. Credit the Mariners for finally getting it.

In Cano, Seattle has reeled in one of the best players in the game by both traditional and analytical standards. Per Wins Above Replacement, only Miguel Cabrera has produced more value for his team than Cano has over the past four years. During that span, Cano has hit .312/.373/.533, which, even after adjusting for Yankee Stadium’s hitter-friendly confines, still produces a total offensive contribution 48 percent better than a league-average hitter. In addition to boasting prodigious power, Cano is also one of the best contact hitters in the league. And while he’ll never get mistaken for Ted Williams, he has posted the two highest unintentional walk rates of his career over the past two seasons, due in part to a combination of pitchers being more careful with him and some iffy Yankees lineups in 2013, but also to Cano improving his approach at the plate. He’s also one of the league’s best glovemen at second base, which should make the Mariners’ top two starters, Felix Hernandez (51.4 percent ground ball rate) and Hisashi Iwakuma (48.7 percent ground ball rate), very happy.

Of course, these are all things Cano has done in the past. When evaluating the merits of a deal for this many years (the contract will end just before his 41st birthday) and this much money, the question is what Cano will do in the future, and whether he’s being paid reasonable market value for those impending seasons.

The cost of a win on the open market is about $6 million right now, give or take a couple hundred thousand. Cano has been a little better than a six-win player over the past four seasons. Even if we peg him as a five-win player, an average salary of $24 million a year would seem a reasonable price for someone that valuable.

The calculation isn’t that simple, of course. Cano might be a five- or six-win player in 2014, but he almost certainly won’t be in 2019, let alone 2023. Then again, just as we have to bake in year-by-year regression as a player ages, we also have to account for year-by-year salary inflation. If we assume a fairly conservative inflation rate of 5 percent per year (which might be low, given the revenue boom in baseball and recent trends), we get … a deal that still looks like it’ll be pretty close to fair market value, assuming Cano continues to perform like a top-10 player for the next three or four years, with a reasonably gentle decline thereafter.

Cano has played in at least 159 games in each of the past seven seasons, making him the most durable middle infielder in the game, and one of the most durable players at any position. That’s a good start if a team is banking on a player to produce through his thirties and into his early forties, given that baseball players tend to peak by their late twenties. It’s also encouraging given that some studies suggest rapid declines for second basemen in their thirties. For example: ESPN Stats & Info looked at the 10 second basemen other than Cano who posted the top WAR from ages 27 to 30 since the start of the Divisional Era in 1961. Since that time frame lines up with Cano’s last four seasons, the intent was to see how the group (Chase Utley, Joe Morgan, Rod Carew, Chuck Knoblauch, Craig Biggio, Bobby Grich, Ryne Sandberg, Lou Whitaker, Dick McAuliffe, and Brian Roberts) fared in their age 31-to-34 seasons. The results?

It only gets worse from there, given how few second basemen remain even close to elite past age 34.

Cano will be in his age-34 season in 2017, and will still have six years left on his deal after that. Given these historical trends, that seems … kind of scary.

The thing is, studies like this are all about framing. There are a few top second basemen who continued to be excellent players all the way through their thirties, chief among them Jeff Kent and Joe Morgan. Though FanGraphs’ Dave Cameron is arguing here in favor of the Phillies giving Chase Utley a contract extension and not backing Cano specifically, the takeaway is the same: There are some exceptional second basemen who have bucked the late-career downtrend and remained very good long past the usual expiration date. To this point, Cano certainly qualifies as exceptional.

Of course, age curves and WAR are a lot of math and a lot of hypotheticals. In real life, the calculations don’t always come out so cleanly. For one thing, just because teams are spending $6 million per win on free agents doesn’t mean that’s a smart decision. I’ll take the under on Tim Lincecum being worth $35 million over the next two years. Plus, that $6 million figure can vary depending on multiple factors, from the position a player occupies to when he signs. A year ago, Providence Journal writer Brian MacPherson found that teams spend $5.5 million per win on free-agent deals signed before New Year’s Day, but just $3.6 million thereafter. (Baseball Prospectus’s Zachary Levine wrote more about the free-agent timing matter on Thursday.)

The bigger issue is that revenue drives salaries; $240 million might seem like an unfathomable sum of money for any baseball player, but MLB is now a $9 billion industry. That money has to go somewhere — either into the owners’ pockets or into a shared system in which the owners and players split the wealth generated by the sport’s popularity. The Mariners have grasped this concept, and are spending big money at a time when team needs and team assets have aligned.

The M’s are coming off four straight losing seasons, with no more than 75 wins in any of those years. They averaged 3.4 million fans a year from 2001 through 2003 (their second, third, and fourth full seasons at Safeco Field), only to see a steady decline that now has them drawing half that over the past two seasons. The team’s payroll has dropped more than 28 percent over the past half decade. Meanwhile, the Mariners are one of a small handful of teams that owns a majority stake in a regional sports network, taking in nine figures a year from Root Northwest to go along with the new national TV money. Rumors circulated two years ago that Seattle might be after Prince Fielder, before the big first baseman finally signed with Detroit instead. Since then, some fans and media members have clamored for the M’s to pursue a big-name player in an effort to revitalize fan interest. That’s a faulty or at least somewhat incomplete premise that fails to consider numerous factors, ranging from the quality of the player, to team needs, to the overall payroll picture.

Right now, however, Cano makes sense for the Mariners on all of those fronts. Even adjusting for Safeco’s pitcher-friendly climate, Seattle finished just 20th in team offense last season. While we need to bake in at least a little potential regression for any left-handed hitter heading from Yankee Stadium to Safeco, Cano’s hit chart shows that he doesn’t hit many wall-scraping dingers. Moreover, Safeco hasn’t been as punitive to left-handed hitters (who tend to hit the ball to right field) as it has to righties (who tend to hit the ball to left) over the years; since the M’s moved the fences in following the 2012 season, it hasn’t been that terrible a park for home runs, period.

The best part for the Mariners, though, is that they have only two players on the major league roster signed to contracts that run past 2014: Felix Hernandez, who’s freaking awesome, and Willie Bloomquist, who isn’t, but whose $3 million final-year salary in 2015 won’t affect the team’s payroll, even if giving him a multiyear deal was excessive. Even if the Mariners are moderately overpaying Cano from a strict dollars-per-WAR calculation, they’re loaded with young, cheap players and had more financial flexibility than almost any other team to take a plunge like this.

They might not be done, either. Sources say the M’s covet David Price and are mulling a big trade offer to get him. Seattle matches up well with Tampa Bay for a potential deal. In Taijuan Walker, the Mariners have a dynamic pitching prospect who offers six years of team control (compared with two expensive ones for Price) and could be a good centerpiece for a trade. Though the Rays now have two catchers signed to multiyear deals, Seattle’s Mike Zunino is a talented prospect who could give the Rays their first long-term solution at that position in franchise history. Nick Franklin could become available, too, now that the Mariners have Cano, given that Franklin broke into the big leagues in 2013 by starting 90 games at second base. Since the Rays have the excellent Ben Zobrist under team control at second base for two more years too, the M’s could also offer a package led by Walker, then trade Franklin separately to address needs elsewhere on the diamond. The end result could give the Mariners a trio of starters in Hernandez, Price, and Iwakuma that would rival Max Scherzer, Justin Verlander, and Anibal Sanchez for the best threesome in the American League while leaving enough payroll space and trade chips to improve elsewhere.

Another criticism that’s been leveled against Cano and the Mariners is that a player of Cano’s status shouldn’t sign with a losing team, while a losing team shouldn’t spend that much money for a player of his status. That’s an oversimplification on both fronts. For Cano, this deal nets an extra $65 million compared with the Yankees’ reported $175 million offer. Given that Washington has no state income tax and New York’s state income tax comes in a shade below 9 percent, go ahead and bump the difference in take-home pay up to $86 million, all told.

What’s more, it’s not a given that Cano is going to a team that will continue to lose, nor that he’s leaving a club that will rip off a bunch of World Series over the next few years. In baseball, past performance doesn’t always guarantee future results. The Pirates and Indians both finished below .500 in 2012, made a series of moves to improve their rosters, then stormed to the playoffs in 2013. The Mariners aren’t a playoff-caliber team just yet, especially with the A’s and Rangers playing in the same division, and the Angels at least something of a threat as well if they can land a couple of quality starting pitchers. But there’s also a long way to go this winter. And even if Seattle fails to make the playoffs in 2014, the Cano signing could pave the way for better team results in the near future. Remember: The Tigers gave Ivan Rodriguez a big-money contract after losing 119 games in 2003; three years later, they made the World Series for the first time in more than two decades.

Rebuilding exclusively through the farm system is a lovely idea. There’s some virtue in signing players to value deals. But the Mariners have been a lousy team for a while, and like 29 other franchises, their goal is to win the World Series, not the dollars-per-WAR championship. Signing the best player on this year’s free-agent market is a pretty good way to start working toward that goal.

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The Cano signing impacts another team, of course. In what condition does this move leave the Yankees?

The Yankees have lost their best player, a catalyst for their lineup and a stabilizing force for an infield that, outside of Cano, was defensively poor in 2013. The infield as it stands is a mess. Heading toward his 34th birthday, Mark Teixeira likely won’t be an impact player anymore, even if he does manage to recover from the injuries that limited him to just 15 games played last season. Shortstop looks like a mishmash of whatever’s left of Derek Jeter and Brendan Ryan, a wonderful defensive player who hits like a pitcher. Third base goes to … Eduardo Nunez? Mike Pagliarulo? The Yanks did pull off a decent low-cost signing with Kelly Johnson, a player with limited on-base skills who can at least play a decent second base and hit a bunch of homers with his own lefty power stroke.

Then there’s the starting rotation, which realistically needs two fairly substantial additions. The Yankees have reportedly agreed to bring Hiroki Kuroda back for one more year; he’s a fine piece, but he’s also entering his age-39 season and coming off a poor second half, meaning he’s probably more of a no. 4 starter than the no. 2 arm he was for the first year and a half of his tenure in New York.

There’s also been talk of the Yankees pursuing another Japanese right-hander, Masahiro Tanaka. The problems: Tanaka is currently a member of the Rakuten Golden Eagles, and Major League Baseball and Nippon Professional Baseball haven’t yet finalized a deal on a revised posting system for NPB players (though they’re getting close); Rakuten might not even post Tanaka this winter; and even if Tanaka does become available, the Yankees would have plenty of competition for the 25-year-old righty’s services.

It’s not all bad, though. The Brian McCann signing might be the best team-player fit of the offseason, given the massive hole the team had at catcher, the deal’s relatively affordable price tag, and how McCann’s ample left-handed power should benefit from Yankee Stadium’s short porches in right and right-center. Jacoby Ellsbury isn’t a perfect player by any means, and he’s certainly no sure thing as a $153 million guy. But the baseball world has been so busy poking holes in the guy that we’ve all apparently forgotten how many at-bats the Yankees gave to poor outfielders in 2013; Ichiro Suzuki was a shadow of his former self, and the less said about Vernon Wells, the better. Ellsbury is clearly an improvement.

Plus, the Yankees certainly aren’t finished spending this winter. With Curtis Granderson off to the Mets for four years and $60 million — not a bad buy for the Mets given some of the money being thrown around this winter, by the way — the Yankees could pursue a strong bat such as Shin-Soo Choo to team up with Ellsbury, Brett Gardner, and Alfonso Soriano, assuming Ichiro is out of a job. Or they could sign Choo and then trade Gardner for help at third base, given how awful the free-agent third basemen are this year. The Yankees could sign quality veteran second baseman Omar Infante and then cover third with a semi-platoon featuring Johnson and others. There are pitchers on the market, too, including Matt Garza, Ervin Santana, and others in addition to possibly Tanaka.

And then there’s this: In sticking to their guns on a seven-year offer instead of the 10 Cano wanted, the Yankees showed they may be edging away from their past tendency to commit to players destined to end their deals years past their prime. The Yankees generate astronomical profits every year, but even they can benefit from occasional fiscal prudence.

Money management aside, the Yankees could certainly end up regretting letting Cano walk. They have many holes left to fill, the free-agent market is starting to dry up, and the competition in the AL East will again be fierce. And now, their best player is gone.