30 edits is a very coarse metric. Some articles would be changed out of all recognition by far less than 30 edits, whilst a vandal magnet like en:Beaver will often be completely unaltered after 30 revisions, (last 37 revisions to Beaver).
Ideally you'd want some sort of fancy algorithm that looks at the amount of change in the article and/or whether some sort of trusted rater had altered their rating or rated it very differently to the average rating from before the latest changes. But at a minimum I would suggest that edits that juts add interwiki links, reverted edits and their reversions be ignored by this process, and that minor edits be given less weight than other edits.