I think a team desperate to compete prior to a major sell off would. The A’s are going to lose a good amount of their pieces this year with guys getting expensive in arbitration...Olson, Chapman, Laureano, etc. This core likely won’t be around next year, and they desperately needed an OF piece to give them a chance.
Also consider, outside of Gallo, impactful OF bats were few and far between. We now know the Rangers wanted a haul of prospects for Gallo. That paired with Gallo galloping around that spacious OF paint a good picture as to why they ponied up for Marte. Not to mention that fact that he costs them $0 this year with Miami paying the remainder of his salary
One last point, Oakland traded for Elvis Andrus this offseason instead of resigning Marcus Semien. Yes, Oakland is a smart team and is pretty protective of their prospects. But no team is perfect, especially not desperate ones