I have a question for you that still unanswered.

I had a competitor who represented 20% of my traffic, they were on my site every single day, they took some parts of my articles, revamped some on their farm links blog, directory articles, etc (Note that they didn't do that on their main site), took also some of design display concept, category titles and off course many terms from my product descriptions.

Since I decided to go out of business and removed my site from internet, their SERP took a huge downfall and it seems like they are ranking nowhere on high traffic keyphrases/keywords.

Today I am wondering if they connected somehow with any black hat tricks to my site.

I know that's a tricky question, but the correlation make me think of a possible breach.

Is anyone could suggest eventual theories that could have damaged my site at the time? Thank you.