diberry - 3:00 pm on Apr 12, 2013 (gmt 0)
My page contained over 100 links, and was #1 for years in that condition, until Penguin. I can only assume that for years it was getting a "pass" on the huge number of links for some under 50 links, and it's been that way for a while (but again, there were lots of other changes, so the fact that it didn't bounce back may not mean anything).
Note that it may not be trackbacks per se, but no-follow links that are the problem. We've been talking about whether a preponderance of no-follow links could possibly hurt your site in another thread: [webmasterworld.com...] This inspired me to look at the backlinks in WMT for this page. They're almost exclusively no-follow (trackbacks) for that page. Other pages with over 50 links on my site have a higher ratio of follow backlinks, and have sailed through Penguin just fine.
It could be that Google is looking at no-follow links differently since Penguin. Maybe they used to have little effect on rankings, but with Penguin they decided a high ratio of no-follow links indicated spam. It IS a spammer tactic to leave silly comments and attempted trackbacks on CMS sites that create a no-follow link with those.
I have deleted that page for now, not knowing what else I can do. It doesn't get rid of the trackbacks, it just sends them to a 404. Many of the backlinks WMT lists for that page don't link to me at all anymore and haven't in years, so I know Google never forgets. I don't know if deleting the page will help, but I'm at a loss what else I can do.