Help With Yoast SEO Plugin?

I'm using the Twenty Eleven theme for a very simple site, and Yoast SEO is having all kinds of issues with it. See here:

It seems like Yoast SEO has quickly become the standard in SEO plugins for WordPress, and I love how it integrates with multisite and copy's the settings from which ever site I choose to all sub-sites.

However, I'm having a problem: the title's like 500 characters long on this new site! Maybe I exaggerate a little. But shouldn't all plugins work with the default theme? Any ideas on how to fix this without modifying the theme? I don't want the fix to get erased every time I update the plugin.

Is help or at least discussion on non-WPMU okay here? I'm new.