SF Giants general manager Zack Minasian told Justice delos Santos of The Mercury News that they will continue to look externally to bolster the rotation. However, he believes that they do not necessarily need to make another addition, and could fill it with an internal option.
SF Giants general manager leaves door open for filling final rotation spot with internal option
For what it is worth, Minasian likely does not want to show his cards if they are looking externally. Plus, this conveys confidence in the handful of young pitchers they have on the roster.