The Athletics acquired Martinez and infielder Euribiel Angeles on Sunday in exchange for pitchers Sean Manaea and Aaron Holiday, Mark Feinsand of MLB.com reports.
The 19-year-old Angeles is viewed as the better of the two prospects heading to Oakland, though Martinez is closer to reaching the big leagues after San Diego added him to its 40-man roster over the winter. Oakland is expected to continue developing Martinez as a starter after he produced a 3.38 ERA, 1.24 WHIP and 122:41 K:BB in 125 innings between stops at Triple-A El Paso and Double-A San Antonio. While Martinez will most likely open the upcoming season at Triple-A Las Vegas with his new organization, the fact that the Athletics have now shipped out Manaea and lost James Kaprielian (shoulder) and Brent Honeywell (elbow) to injuries this spring could give the 25-year-old right-hander and outside shot to crack Oakland's Opening Day rotation.