Punting average CAN work because guys that hit for low averages last year (like Ian Kinsler, David Wright, Evan Longoria, Carlos Santana, Hanley Ramirez, etc.), are fully capable of hitting for a much higher average.
You just never know, any guy can hit for a decent average. Even Jose Bautista (a career .254 hitter INCLUDING last season) hit over .300 last year. So you just never know who is gonna surprise you.
Not to mention you are playing a H2H league so guys go through hot streaks and cold streaks all the time.