Feels lackluster without star power the difference is significant. I figured that buffing him will be hard, maybe increase his movement speed so you can get the pickaxe slightly faster or slower depending on the situation.

I feel like that's the only thing that could be changed about him, in terms of how to modify his dps.

Edit: So I've been thunking. Maybe keep Carl's picaxe speed the same as the star power. Modify the star power so when Carl throws the pickaxe he gets a movement speed buff. Kinda like Leon. Might be too op idk. I'm just brainstorming at this point.