SERP dropping along with competitors - Google algorithm mix up?

[amandadgr]

I am hoping someone will have some insight as our recent ranking drop has been driving me crazy trying to figure out what happened.

Our site is www.dgrlegal.com. We've been building links by creating quality content and getting others to link to it. We've seen our rankings rise to 3 for a number of keywords. Suddenly around March we saw a pretty drastic drop but only for certain keywords (maybe a Penguin hit?). For example, "new jersey process service" still has us ranked 3rd but "new jersey process server" sees us much lower around 19.  I've noticed several competitors have dropped while one has risen so is this negative SEO? Probably not as our backlink profile doesn't seem suspicious but it has me very confused.

We've received no warnings or notices from Google.  The only thing I see is that our indexed pages went from 13 to 98 in January and have been now steadily increasing to 129, although I thought this would be a positive.

Any suggestions or thoughts? I thought maybe things would shake out but it hasn't happened as of yet - we just keep dropping.

[Njave_MCP]

What seems here is that your duplicate content might poise the problem. Have you used any SEO tools to remove archives, tags and such from being accessed by crawlers? From what I know search engines don't like sudden spikes in anything! Be that inbound links, outbound links, content pages or anything in between. But check the first idea I told you about, maybe it helps.

[amandadgr]

Thanks so much for the feedback. I haven't done a thorough check for duplicate content so I'll do that now and test out what happens.

Thanks again,

Amanda