Start Keenan Allen or Mike Williams?

1/2 ppr.
Going into tonight’s game I’m down 26.1 points. I have J Herbert and one WR slot open and my opponent has Jared Cook.

I’m tilting a bit. I have both Keenan Allen and Mike Williams and need JHerb + one chargers WR to outscore jared cook by 26.1 to win.

Should I start Mike for upside or don’t get cute and stick with Keenan?

Best boom chance is Mike Williams. Floor play is Allen.

Williams was like the WR2 in fantasy coming into Week 4; I don’t see how you don’t start him.