SAN DIEGO — Former home run king Mark McGwire says it’s “a great challenge” to be hired as bench coach of the San Diego Padres.

McGwire becomes rookie manager Andy Green’s right-hand man in the dugout after spending the last three seasons as hitting coach of the rival Los Angeles Dodgers. Before that, McGwire was hitting coach of the St. Louis Cardinals for three seasons following a hiatus after his steroid-tainted playing career ended.

Big Mac said during a conference call Wednesday that he brings “a lifetime of experience” to his new job.

“As a player I pretty much went through anything a player could ever wish upon as far as success, and all the failures,” he said. “You learn how to be a man through adversity and failure. The game is built on failure. I know how to bust through that. … I’m ecstatic about this new role. It’s a great challenge for me, moving up in the game.”

TRADES: Baltimore added a bat as protection in case it loses Chris Davis, acquiring power-hitting Mark Trumbo and left-hander C.J. Riefenhausen from Seattle for catcher Steve Clevenger.

Oakland obtained first baseman Yonder Alonso and left-hander Marc Rzepczynski from San Diego for left-handers Drew Pomeranz and Jose Torres plus a player to be named.

The Indians acquired outfielder Collin Cowgill from the Los Angeles Angels for cash and designated left-hander Nick Hagadone for assignment..

Kansas City acquired backup catcher Tony Cruz from St. Louis for infielder Jose Martinez.

MARINERS: Seattle agreed to a one-year contract with outfielder Nori Aoki, according to two sources. Aoki was limited to 93 games with San Francisco last year due to a broken right leg and a severe concussion in the second half of the season.

Seattle also agreed to a $750,000 deal with reliever Justin De Fratus, who became a free agent after the season rather than accept an outright assignment to the minors by the Phillies.

BRAVES: Veteran infielder Gordon Beckham, an Atlanta native and former University of Georgia standout, agreed to a $1.25 million, one-year contract with the Braves, pending a physical.

PHILLIES: Philadelphia claimed outfielder Peter Bourjos off waivers from St. Louis.

There were 206 players eligible for arbitration at the start of the day. Any player offered a contract is entitled to, at a minimum, roughly one-sixth of his 2016 salary as termination pay if he gets released.

Among those who became free agents when they were not offered contracts were injured Kansas City closer Greg Holland; Oakland first baseman Ike Davis; Detroit right-handers Neftali Feliz and Al Alburquerque; White Sox catcher Tyler Flowers and right-hander Jacob Turner; and Cincinnati right-hander Ryan Mattheus.

Arbitration-eligible players who agreed to one-year deals were Dodgers catcher A.J. Ellis ($4.5 million), Toronto first baseman Justin Smoak ($3.9 million), Baltimore right-hander Vance Worley ($2.6 million), Oakland left-hander Felix Doubront ($2 million), Cubs left-hander Rex Brothers ($1.42 million) and Washington first baseman Tyler Moore ($900,000).