Seth Smith has hit 30 doubles so far in 2015, which is a very respectable amount of two-baggers. This ties him for 35th-most in all of MLB and is good for third place on the M's (behind Cano and Seager who have 34 and 33 doubles, respectively). This number becomes even more impressive when you recall that Smith has only had about 2/3 the plate appearances of an everyday player. (When looking at Seth's numbers from this season it's important to remember that he has experienced a platoon advantage in ~88% of his at bats; that being said, his doubles rate against lefties is actually higher than it is against RHP in 2015.)
In fact, his 30 doubles in just over 400 plate appearances gives him the second highest doubles rate in all of baseball (among the 219 players with 350+ PA). His rate of one double every 13.6 PA is only bettered by that of Michael Brantely (13.1 PA/2B). Smith is able to collect so many doubles because he has the ability to smack line drives all over the field. His 11 opposite field doubles are the most on the Mariners.
In addition to have having a great doubles season this year, Seth's doubles rate in 2015 is historically high for a member of the Seattle Mariners. His PA/2B currently ranks as the fifth best in franchise history. You know you're doing pretty okay offensively when you're grouped with Alex Rodriguez and Mr. Double himself.
To make things even better, Seth also smacks his share of home runs and legs out more than his share of triples. Only 32 MLB players have more triples than Seth Smith. (This is a fact that I enjoy immensely but also one that seems fairly ridiculous - Seth Smith is not a fast man!) As such, Seth is also among the league leaders in plate appearances per extra base hit. He's currently tied for 10th in all of baseball (min 350 PA) with one XBH every 8.9 PA.
*All of the numbers used in this article are valid through 9/17/15. They do not include yesterday's games.
Again, Seth finds himself amidst some really good company. He's tied with super smashers Mike Trout and Edwin Encarnacion and ahead of dinger destroyers like Chris Davis and Nelson Cruz. This isn't a particularly new thing for Smith. He's always been much better than average at smacking extra base hits. He's just been an especially competent doubles monster in 2015.
Seth seemed like a solid pickup this past offseason and he hasn't disappointed. He's been a pretty dependable bat in the Mariners lineup in 2015 and although he's slumped a bit as the season has waned (wRC+ of 85 since the beginning of August) he's still a solid 2-win player who can hit the ball, doesn't embarrass himself in the outfield (generally), and is under club control at a team-friendly rate through 2017. That is a very useful player to have.
Keep getting/smashing/enjoying those doubles, Seth. Go M's!