Rivas showed advanced feel to hit and a polished approach at the University of Arizona, selected by Oakland in the fourth round in 2018. That carried over to his pro debut, as Rivas slashed .285/.397/.383 in the New York-Penn League, walking nearly as much as he struck out. It has been more of the same this season for the 22-year-old, who skipped over Low-A entirely but still placed on the California League all-star team after a strong .282/.401/.414 performance in the first half.
There’s limited present game power, though Rivas could add more by changing his swing for more lift. He has the chance for an average or better hit tool, spraying line drives to all fields from a sweet left-handed swing. Rivas is a patient hitter, consistently walking at a plus clip without excessive strikeout numbers. Defensively, he’s an above-average 1B with good footwork and a strong arm, mobile enough to get some reps in the outfield as well. Avoiding a 1B-only label would help his offensive profile considerably, as Rivas will always have more hit than power. The absolute best-case ceiling is an everyday 1B in the mold of James Loney, though the lack of power or defensive versatility could make Rivas a bat off the bench.