I suspect that you have so many of these 404s on your site that Googlebot is spending ALL of its time crawling them and not spending any time crawling your content. If I am right, the number of documents indexed (WMT -> Health -> Index Status) would have fallen.
I would suggest putting in rules to redirect any of these 404s as best you can to appropriate content (not to your home page). If you redirect these 404 urls then *perhaps* googlebot will figure the situation out faster.
RedirectMatch 301 ^(.*)[0-9]+$ http://example.com/$1
RewriteRule ^(.*)[0-9]+$ http://example.com/$1 [R=301,L]