Notable difference between crawled and indexed pages

First of all thank you for taking the time to read my question and hopefully help me out a little.

We've started BeatsandBeyond.com back in 2010 and for the first couple of months we saw a steady increase in visitors. Just as with many sites the growth decreased a little, but we kept writing and publishing stories and late 2012 we released a new website.

From that moment on though, something strange happens. We launched the new website September 30th, about a week later October 7th I see an enormous rise in crawled and indexed pages. I never really thought to look deeper in to it and we just kept publishing our stories. The amount of visitors was still steady so we just kept going hoping to gain more backlinks, likes, tweets and who knows what on our way to reach a bigger audience. However, over the past couple of months we saw a steady decline in visitors and my re-sparked interest in all things SEO (and little bit of extra spare time) led me back to Webmaster Tools to dig a little deeper. There I came across this graph below which led me to believe something is wrong.



How is it possible there are so many more crawled pages then indexed pages. And why don't the amount of indexed pages grow? We publish almost on a daily basis so you would expect a steady incline there, but it seems to be slowly decreasing instead.

I hope someone here is willing to help since I have no clue by now. After focussing on great content feel my solution to getting more visibility in the SERP's might be here.

Thanks in advance, I hope someone can shed some light on this or maybe reassure me nothing is wrong and that this is completely normal.