This is not uncommon. It's hard to say specifically what this has happen to your home page but here's some possibilities (and it may be more then one of these):
1) It's a temporary drop while Google processes a bunch of information about your site and the site around yours. This drop may last a few days or a few weeks.
2) Incoming links to your site have been removed, de-indexed, nofollowed, or devalued.
3) The pages ranking ahead of you got more links or higher value links.
4) The pages above you improved their on site SEO including adding more content to your website which links back to their home page, better internal linking, better semantic markup, etc.
Don't go and do anything rash because of this. Keep adding content to your website (if possible) and seeking incoming links from related websites.
FYI, meta tags and page views do not affect your rankings at all.
Have you checked Google's Webmaster Tools to see if there are any messages for you from Google? They do report serious problems there. It's worth a short to look.