If someone could do “something” on your website, they are not spammers but hackers. Usually spammers only leave comments to get publicity but they don’t steal I guess.
As long as you are updated to the latest version of wordpress then chances are very low for a hacker to attack.
Perhaps the explanation of lower hit is the missing spike of traffic from search engine? May be you wrote something very interesting that search engine keep sending your traffic and that create a spike of traffic however when the topic gets old and it get lesser hits?
