I think the star rating system is fine apart from the phrasing; As Donoreo suggests , I agree '* Below Average' and so on up to 5* Excellent POTD material.

The star rating, in my opinion should be abled without any need to comment as a way for quick response, so that those with little time to spare can simply show appreciation rating and move on to the next thing they wish need to do.

Given the low numbers who stop to comment on POTD, or indeed cast a vote in the Weekend competition, I assume it is an aspect of available time, rather than any general sense in apathy towards taking part.