I agree completely, anecdotal evidence is weak at best. However, all you've given is statistics of an irrelevant sort, and I don't believe that's any better. You might as well say the sky is blue, therefore Chicago sucks because of Obama. Obviously, that's a stupid thing to say.

In 2007 (a year for which data is available on Wikipedia), the murder rate in Chicago was 15.6 per 100,000 individuals. About twenty five years earlier and shortly before Obama became a community organizer (and the data closest to 1985, Obama's first year as a community organizer, I can find on the first page of google), in 1983, the rate was ~22/100,000 people. Chicago was safer, so far as homocides go, after Obama than before him.

Of course, this safety cannot be attributed to Obama, nor can the violence that exists in the city. None-the-less, if you're going to blame Obama for all the violence in Chicago, I'm not sure how you can ignore the fact that violence in Chicago has decreased since Obama has come on the scene.