Hernandez's average annual value of $25 million remains tied for fifth all-time, while Cano would be tied for 10th with his $24 million annual average, if his new figures are correct.
That's a lot of cash for two players, but the Mariners aren't totally new to big deals.
Ichiro Suzuki averaged $18 million a year on the five-year, $90 million deal he signed with Seattle in 2008, which made him one of the higher-paid players in the game at the time at age 34. Ichiro had already established himself as a Mariners icon when he renewed, having been a seven-time All-Star and seven-time Gold Glove right fielder.
Ichiro added three more All-Star berths and Gold Glove Awards in his first three seasons of his big deal, then failed to reach 200 hits and batted a career-low .272 in the fourth season before being traded to the Yankees midway through the last year of his contract at age 38.
Cano, who just turned 31, will be under contract through age 40 if he plays the full 10 years in Seattle.
Ichiro's contract stood as the biggest in franchise history until Hernandez eclipsed everyone with his $175 million extension last February, which was the most money ever paid for an MLB pitcher until the Tigers gave Justin Verlander $180 million a month later.
While salaries have escalated considerably in recent years, the Mariners made a relatively large leap into the free-agent pool in December 2004 as well when they signed third baseman Adrian Beltre to a five-year, $64 million deal one day after inking first baseman Richie Sexson to a four-year, $50 million agreement.
At the time, Seattle was coming off a 63-99 season and looking to jumpstart an offense that had finished last in the American League in scoring.
Beltre had hit 71 home runs and 203 RBIs in his previous two seasons with the Dodgers and was just entering his prime at 26. But while Beltre brought a tough presence and outstanding defense to the Mariners, he wasn't able to duplicate the same level of offensive production at Safeco Field, which traditionally has been tough on right-handed hitters.
Beltre hit .266/.317/.442 in five seasons in Seattle while averaging 21 home runs and 79 RBIs. Since leaving the Mariners in 2010, he's batted .314 and averaged 26 home runs and 100 RBIs while playing one year for the Red Sox and three for the Rangers.
Sexson provided some right-handed thump his first two seasons after signing his contract with Seattle, hitting .263 with 39 home runs and 121 RBIs in 2005 and .264 with 34 homers and 107 RBIs in '06. But the big first baseman saw his numbers slump to .205 with 21 homers and 51 RBIs the following year and he wound up getting released in mid-July of the final season on his deal after those struggles continued.
Most of the rest of the Mariners' history with big contracts involves players who departed Seattle to take big money elsewhere. Alex Rodriguez took a 10-year, $252 million deal with the Rangers in 2001 after spending the first seven years of his career with the Mariners.
That deal, along with a $275 million extension Rodriguez signed with the Yankees in 2008, are the only deals in MLB history larger than Cano's reported $240 million pact, which equals the 10-year deal Albert Pujols signed with the Angels two years ago.
Ken Griffey Jr. played his first 11 seasons in Seattle, but that was a different era and he was earning $8.7 million in the final year of his first stint with the Mariners in '99. Griffey then signed a nine-year, $116.5 million deal with the Reds that was one of the largest contracts in MLB history at the time, before returning to Seattle for his final two seasons.