So, somewhat like Illinois, it was low turnout + those that turned out were mad at the state level about tax increases and the sluggish state economy, in addition to a bad national landscape for Dems?
Sure, but it's important to recall that in Illinois, Quinn was very unpopular and Rauner was a moderate who worked hard to win support from Democrats. Elections are almost never decided by a single factor. Turnout probably played a much greater role in Maryland than in Illinois.
Plus, as KCDem said, Brown ran a pretty awful campaign.