The A's Trade Yonder Alonso to the Mariners for Virtually Nothing

The Seattle Mariners picked up an All-Star first baseman for peanuts.

That's the big takeaway from the deal completed by the M's and the Oakland Athletics, with Seattle sending minor league outfielder Boog Powell to Oakland in exchange for Yonder Alonso, who represented the American League in this year's All Star Game. He's enjoying a banner year in 2017, already racking up a career-high 22 home runs. In fact, it's the first time in Alonso's MLB life that he's had double digit dingers, his previous career high being 9.

In 371 plate appearances, Alonso is batting .266/.369/.527 with those 22 bombs, 52 runs scored, and 49 RBIs. He has a weighted on base average (wOBA) of .374, a weighted runs created (wRC+) of 140, and has been worth 2.0 WAR.

Alonso is part of a growing pool of players who are walking more, striking out more, and hitting more taters. Here are his numbers from the last three seasons, when he essentially became a Major League regular.

Alonso's ground ball percentage has seen a staggering drop, from 49.2% two years ago to 32.5% this year. Correspondingly, his fly ball rate has skyrocketed, from 27.8% in 2015 to 45.5% in 2017. It's the main reason (other than possibly juiced balls, denser bats and smaller ballparks) why he has seen such a dramatic uptick in his offensive production.

All that said, since the All-Star Game, he has seen his struggles. In 73 second half plate appearances he's batting .230/.356/.377, with just two homers and three doubles. The on-base percentage is still really nice, but the rest of his numbers are way down from his red-hot first half. So was that first half a mirage? Was it a hot couple of months from a player who was outperforming his career numbers?

Both his walk rate and strikeout rate have increased slightly, but not to an alarming degree. The main problem has been his batted ball data. He's once again hitting a majority of balls on the ground, at a rate of 42.9% in the second half, up from his first half number of 30.2%. And, of course, if there are more grounders being hit, that means fewer fly balls, with a decrease in his fly ball rate from 48.7% to 31.0%.

For Seattle, this is a no-harm, no-foul move. They give up a DH/OF in Powell who has batted .194/.310/.194 in limited MLB action this year (just 43 plate appearances). In 58 AAA games, the 24-year-old hit .340/.416/.490 with just six home runs.

The M's will likely lose Alonso at the end of the season as a soon-to-be free agent, but as for now, he helps form a platoon at first with right-hander Danny Valencia.

The Mariners are in the AL wild card hunt, just 1.5 games behind the Kansas City Royals for that final spot. Adding Alonso gives them another power bat, provided he can remember how to hit the ball in the air again.