At Low A in his age 19/20 season, Vielmas OPS'd .636. Didi Gregorious (who was 4th amongst all qualified SS this year in WAR, and has a similar below-average offense, good-to-great defense profile) in his age 20 season OPS'd .694 at low A and .561 at high A. Last year, Vielma in his 20/21 season was at high A, and OPS'd .627, whereas Gregorious was at .791 at high A, and .704 in AA. That being said--Gregorious played in the Cali league for high A; both years he was there, ever team OPS'd over .729. Last year in the FSL, no team OPS'd over .700. Both Vielma and Gregorious were in the Midwest League for A ball, except when Didi was there, 10 team OPS'd over .700, and in 2014 when Vielma was there, only 6 did. Vielma is not as good offensively as Didi, but he's certainly not far off, and can clearly be a valuable contributor if he continues to progress.