Segura is also much better defensively than Cesar by OAA, and in a test, Jonathan Judge of BP found OAA to be best at measuring infield defense, FRAA for outfield defense (https://www.draysbay.com/2020/4/15/21219514/mlb-defense-best-statistic-baseball-prospectus)
DRS has segura at 5, Hernandez at -11. THat definitely is what it felt like last year. OAA had Segura at 9, Hernandez at 0.
Hernandez also certainly didn't look amazing at 2b last year, and Segura can swing SS. So offensively, I think it's fair that segura and hernandez may be equal. I don't buyy that for defense.