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Having said the above, it is an opportunity lost. Mix them up a bit.
Regarding your question about 'penalties' try thinking of it in a slightly different way. If before you were doing something that involved a lot of repetition of important keywords, you may have benefitted from it, perhaps more than you "should" have. Some believe, myself included, that in more recent G updates (or whatever they're called now), algo elements have discounted more of that sort of "cheap SEO."
Whether sites have received true "penalties" has been a topic of some hot debate, though it's my perception that most senior members in here are skeptical.
Rather, what might be happening is that if G sees what it considers "over repition" of some keywords, the page may not appear for those keywords. *If* this exists, it's probably not related to one specific element of your site, but a combination of elements done to excess, (since for almost any single component, e.g. Titles, there are exceptions that disprove penalty theories).
If a page is lost for over repetition across multiple site components, many call that a penalty. But in fact, it's simply a variation of an algo that seeks to clean some of the rampant spam out of the SERP's. Also, there's the possiblity that most of the recently lost pages have little to do with new filters, and more to do with issues related to G's attempt to better "understand" word variations and language in general.
So far, the effectiveness of G's recent effort to clean some of the spam has been a failure (IMO), characterized in part by far less relevant SERP's for *some* searches, and the ongoing presence of some of the worst spam offenders on the Web. Cloakers for example, are doing better than ever.