The Seattle Mariners agreed to a 10-year, $240-million contract with free-agent second baseman Robinson Cano Friday, opting for an exclamation point, not a period, at the end of baseball’s most frantic week of off-season activity in years. The New York Yankees never came close to matching what turns out to be one of the four or five richest contracts in sports history. After nearly two days of percolation and a violent series of twists and turns Friday morning (caused mostly by bad reporting from Mark Feinsand of the New York Daily News), Seattle GM Jack Zduriencik got his man, and baseball’s newest mogul, Jay Z, got his man his money.

As they always do, critics came out of the digital wallpaper to shout down this (admittedly risky) splash. Any 10-year commitment makes the baseball fans weaned on two decades of marginal-cost analysis and aging-curve calculations balk, and $24 million per annum is an awfully big number for a second baseman who begins the deal on the wrong side of 30. There was no way a team other than the Yankees could have signed Cano and not felt the wrath of Baseball Twitter, and even if some team could have eluded mockery, this team is not that one. The Mariners have taken some very hot heat for making this aggressive an addition right now, when they seemingly lag 10 or so wins behind their chief competitors in the AL West.

For those who might not understand just what this means, Cano is the league’s best second baseman. He’s 31, and so due to age somewhat quickly, but he had a perfectly typical season in 2013, no slippage, and no injuries—he remains one of the most durable players in baseball.

He’s never struck out more than 14.1 percent of the time, in any season. He uses the middle of the field, which makes him hard to defend, and therefore, he reaches base at about a .340 clip when he puts the ball in play. While not a classically patient hitter, Cano has posted unintentional walk rates just north of 8 percent the past two seasons, and has seen more pitches without swinging and missing more. There is no safer bet, at any time or in any season, to hit .300 and get on base at a .370 or better clip.

Cano’s power is noteworthy, too, though, and it may well be that no left-handed batter in baseball is better-equipped to weather the move from Yankee Stadium to Safeco Field than he. He doesn’t pull the ball in the air very often; he doesn’t rely terribly heavily on fly balls at all. Cano has just 207 career home runs, but 375 doubles. That 375 figure is the sixth-highest doubles total in history through a player’s age-30 season, and it came in nearly 300 fewer plate appearances than any other player on the top-10 list. It’s unlikely that Cano will break the all-time doubles record, but far from impossible: He would simply need to be the fourth-most prolific doubler from age 31 onward.

Those doubles are the most important and telling stat on Cano’s line. They express the approach he uses, the simple, fluid violence of his swing, his line-drive proclivity, his relative lack of size and strength (how many of today’s best hitters stand a flat six feet, and weigh only 200 pounds?) and the reasons for which he’s actually somewhat underrated. Robinson Cano wasn’t getting anything from playing at Yankee Stadium, and he’s going to keep being one of the best hitters in baseball for at least another year or two.

Now, there are reasons for caution and concern here. Cano has been unbelievably durable thus far in his career, especially for a second baseman. When it comes to second basemen, though, every game played is a mile or 10 on the odometer. Second basemen peak earlier and age less well than any other type of player, and the things that make second basemen so different from most other players on the diamond–they usually lack the arm strength or quickness of reaction time to play shortstop or third base, but also lack the foot speed to play center field–apply in full to Cano. While not large, Cano is also thick-bodied. That may not ever be an issue, or it may augur badly for his ability to hang onto what are, right now, excellent defensive skills.

Those concerns kick in in, perhaps, Year Three or Four of this deal. For the first two seasons, Cano will remain a superstar, and such tremendous reliability from a player this good demands to be paid for handsomely. The Mariners might have extended themselves a bit sooner than is the custom, but this is the right kind of player for whom to do that, and to me, the Mariners are in the right spot to break with tradition.

The Los Angeles Angels of Anaheim signed Albert Pujols and C.J. Wilson in a desperate attempt to push back against the Texas Rangers, who had just won their second straight American League pennant two months before the Angels’ spree. That team had Erick Aybar, Howard Kendrick and Jered Weaver as its core, albeit with Mike Trout in the wings. Signing Pujols and Wilson didn’t apply financial strain, per se, but it began to bind their roster. They didn’t have a ton of flexibility, in terms of roster space or in terms of contract commitments. The Pujols deal has gone horribly awry, but Pujols’ struggles with injury and decline are only the proximate cause. The principal cause is that the Angels were committed to too many expensive, mediocre players when they made that addition, and they couldn’t reshape their roster nearly fast enough around Pujols.

The Texas Rangers, over a decade ago, made a similar mistake with Alex Rodriguez. They chose precisely the right guy in whom to invest. Rodriguez was the best player in the American League–the best in baseball, at the moment he signed the deal, as Barry Bonds had not yet begun his career’s superhuman final act. He was 25. He performed the Hell out of that deal. The reason that the Rangers couldn’t capitalize on that contract wasn’t the contract itself: It was that they had failed to assemble anything resembling a competitive MLB pitching staff. They were an imbalanced team, and signing Rodriguez not only failed to address the imbalance, but took up such a large percentage of the team’s resources that fixing the pitching became a practical impossibility. It’s telling that, when the Rangers gave up on Rodriguez after three seasons, they again failed to target any pitching improvement.

Big contracts aren’t poisoned pills. They just tend to be issued by front offices that think too ham-fistedly, too heavy-handedly, and as a result, they also tend to leave a roster lurching, creaking and out of balance. The Mariners aren’t such a team. While the wisdom of this front office might fairly be questioned, consider the positional core around Cano:

• C- Mike Zunino, league-minimum salary, 23 years old for 2014
• 1B- Justin Smoak, projected to earn $3 million in arbitration, 27 years old for 2014
• 2B (backing up Cano, for now)- Nick Franklin, league-minimum, 23
• 3B- Kyle Seager, league-minimum, 26
• SS- Brad Miller, league-minimum, 24
• LF- Abraham Almonte, league-minimum, 25
• CF- Dustin Ackley, league-minimum, 26
• RF- Michael Saunders, projected to earn $2 million, 27
• DH- Jesus Montero, league-minimum, 24

Now, Almonte, Ackley and Montero have been either bad or unable to establish themselves thus far. All three are in varying degrees of danger of being replaced. Still, that’s a group of position players who offer a lot of flexibility, and thanks to their age, there’s also upside, in Miller, in Zunino and in Smoak.

The Mariners also have a really good group of pitchers at the front of their pitching staff, with Felix Hernandez and Hisashi Iwakuma two of the AL’s top 10 starters and Taijuan Walker one of the game’s five best pitching prospects. They’re thin in spots, but light-years ahead of the 2001 Rangers, for instance, and they have a stable of power arms in their farm system and in their bullpen.

This team, so cheaply assembled until now, also has new money pouring into its coffers beginning this season. They not only got the bump (of roughly $27 million) that everyone got from the rise in national-TV revenue split among all teams, but begin their own, regional TV deal that enriches them by about $100 million more per year than their last one did. Cano simply doesn’t disrupt this team’s ability to spend money whatsoever, and there’s talent here that will let them build without overreaching.

The Mariners won 71 games last season. They haven’t seen the playoffs since 2001, Ichiro’s first season in the Major Leagues, and their first year without Alex Rodriguez. Signing Cano makes them better. It doesn’t make them as good as the Oakland Athletics, who have made a quartet of quality additions this winter, although none so splashy, or the Texas Rangers, who have spent the winter striving to realign their talent, and seem to have gotten it right. If Seattle wants to contend right away, their work is far from done.

The MLB Winter Meetings begin Monday in Orlando, and the Mariners and Rangers figure to be the two hottest pursuers of Rays ace starter David Price. They also might end up the two highest bidders on the top free-agent hitter who remains, Shin-Soo Choo. The Mariners have to win some of these tussles. After years upon years of backing down when the stakes rose too high for their taste in both free-agent and trade negotiations, Seattle has to be willing to call or raise at every turn during the winter-long poker game to come. Signing Cano is a dazzling, thrilling first move, one I failed to anticipate but fully appreciate. It must be just the first step, though, or it won’t mean much.