Total bases corresponds closely enough to slugging pct we can just use that.
so which is better OBP% or SLG% for a hitter. Probably just as important for a pitcher.
With a SP you do have the added factor of fatigue. High OBP in the form of walks runs up pitch count and with advanced fatigue turned on that pitch count can lower the F? rating earlier in the game making bullpen used more. But extra base hits lead to runs faster. So I consider both equally important.
Traditionally, OB for hitters is seen as somewhere between 1.5-3 times more important to run scoring that slugging. Since Slug = TB/AB, TB is basically Slug.
That said, you don't want a guy who gives up a lot of bombs...