Yeah if he's a middle of the rotation starter that has gotten lucky, then Soroka has gotten lucky to some extent too.
Castillo: 2.41 ERA, 3.67 FIP, 3.72 xFIP
Soroka: 2.24 ERA, 2.95 FIP, 3.60 xFIP
Soroka's xFIP-ERA split is even bigger. Although FIP probably does tell the story better on him.