Robinson Cano's 10-year, $240 million deal with the Seattle Mariners, which was first reported by Enrique Rojas of ESPNDeportes (Spanish link), ties him with Albert Pujols for the third-highest contract ever handed out to a major league player—Alex Rodriguez holds the record for the first two spots.
While there are plenty of examples of players putting up elite numbers into their late 30s, it's still a significant risk for the M's because of the likelihood that they'll be paying Cano top dollar for at least a few seasons when he'll no longer be in his prime.
For every David Ortiz, who had a .959 OPS with 30 homers at the age of 37, there are several formerly great players who were out of the game by their early-to-mid 30s because their skills had diminished to a point where they could no longer produce league-average numbers.
Contracts of this magnitude—years and dollars-wise—are still relatively new, with the contract of Derek Jeter the only one among the 10 highest of all time that has expired. Therefore, it's hard to point at any and declare Cano's deal as a huge mistake by the Mariners.
But for what the players on this "10 Richest Contracts In MLB History" list have done on the field thus far and where they appear headed over the course of their deals, it's not too early to pass judgment and place a grade on their impact.
Each of the 10 slides contains contract details, average WAR per season over the course of the deal, a summary on the player's impact and/or potential impact and a letter grade.