Should I request the comment be deleted or learn my lesson? What is the lesson to be learned? Do I need to comment on lower page rank blogs?
It may just be a coincidence that your site lost PR while a blog you linked to ranked higher than you. By coincidence, I mean that there are many factors at play when it comes to serps listings and PR. It could very well have been the google algorithm found some duplicate content on your site which would have devalued you in the last google panda update. Or maybe you submitted to many backlinks all at once and google penalized you for backlink spam.
It's just hard to really know what happened, but as others have mentioned, while blog commenting has been devalued, a single blog comment won't damage your site in the way you're saying yours has been. It would of had to of been bulk backlink submission spam, keyword stuffing, duplicate content, keyword cloaking, previous backlinks dropped / removed, linking to bad neighbor sites from your site, participating in link farms, etc.. Again, many factors at play that could damage your serps & or PR placement.
I would suggest that you stop thinking so much about the PR metric and focus more on the bottom line of why we are in business in the first place, which is $$ (ROI) Return on investment $$. I have PR0 sites that make more than my PR4 sites any given day of the week. PR has no baring at all on how much money a site can or will generate and therefore becomes a useless Vanity metric that only confuses people and detours them from actually focusing on getting their site(s) to convert visitors.
In the future to avoid a fluctuation like you are experiencing now, simply make sure you are providing unique content not used anywhere else and approach your site promotion efforts more ethically with less manipulation in mind. The end result may take a little longer to achieve page 1 / #1 spot, but once you hit it, you'll stay there much longer.
Also, don't forget that (SEM) Search Engine Marketing is an ongoing event. Everyone wants the top spot, so naturally you'll always have competition looking to take your spot away from you. Once you stop actively promoting your site(s) for a little while it's natural for others with similar niches to pass you up that still promote.
Just like in the olympics, boxing, wrestling, nascar, or other sports; you may have won 1st place (gold) this time, but chances are you won't win every time and a new champ will be crowned eventually.
Not sure if that helps any, but just my thoughts on this topic.
Eric Lyon
