It's actually really wise by Roberts, isn't it? Assuming he can only start once more this series, you'd rather him start on full rest than not. And you're not worried about the series not going to his next game because it has to go minimum 6 games if you're the Dodgers and losing. it means he's likely not a relief option in game 7 Sure, but if I'm the Dodgers I'd rather him start his game on full strength than potentially screwing him up on the off chance it goes 7 and he is even needed for high leverage innings there.