Not having power correlates with poor performance quite strongly, but it may also correlate with worse players.
I don't think you really mean "worse players," because if someone doesn't own power, it doesn't mean they are necessarily worse than someone who does own power. I've seen some pretty bad players with full power and Shops and some great players with unpowered Fish. I think lack of power corresponds more to players new to Vintage ("inexperienced" is a better word in this case), or players who don't get a chance to play a lot of T1, which makes the purchases not worthwhile