Mark Simon has a good piece on Kyle Seager's improved defense for the Mariners this year, improvement that has helped turn Seager into one of the most valuable players in the American League.

Too bold of a statement? I don't think so. Here are the AL Wins Above Replacement leaders via Baseball-Reference:

Mike Trout: 6.3

Josh Donaldson: 6.1

Felix Hernandez: 6.0

Chris Sale: 5.3

Corey Kluber: 5.2

Robinson Cano: 5.2

Kyle Seager: 5.1

Max Scherzer: 4.9

Adrian Beltre: 4.9

Michael Brantley: 4.8

On FanGraphs, Cano ranks fifth among AL position players (4.7) and Seager seventh (4.5). Maybe they're not strong MVP candidates -- not in a league with Mike Trout and teammate Felix Hernandez -- but the Mariners are certainly more than a one-man team.

Seager's numbers may not blow you away -- .279, 18 home runs, .344 OBP -- but he ranks 13th among AL hitters in park-adjusted wRC+ (weighted Runs Created). So he's one of the better hitters, he's been durable (he's missed just three games) and he's a plus defender at an important position; that creates a lot value. WAR also doesn't factor in that Seager has done a good job with runners on base, hitting .313/.371/.514.

It will be interesting to see how Seager finishes; he was having a similar season last year before cratering with a .196 average in August and .172 in September.

As for Cano, the story line for first two months was his lack of power -- he had just two home runs through Seattle's first 60 games. He was hitting for average but not pulling the ball with any authority. After a minor slump dropped his average to .319 on June 29, he's been on a terror, batting .357/.444/.579 with six home runs over his past 37 games. And remember, considering Seattle's lack of production from the first two spots in the lineup -- the Mariners are 27th in OBP from their leadoff hitters and last in OBP from their No. 2 hitters -- pitchers often have the luxury of working around Cano or working very carefully to him.

The fact that he has 66 RBIs is pretty remarkable. But he's done that by hitting .360/.491/.709 in 114 plate appearances with runners in scoring position. (Cano is tied for 72nd in the majors in number of PAs with RISP; Adrian Gonzalez leads with 171.)

Overall, Cano is posting a career-best .398 OBP that ranks fourth in the majors among qualified hitters. His wRC+ is 142 -- the same as last year.

He's having a great season.