What do we mean when we say the New York Times, the Washington Post, NBC, CNN, etc., are "in the bag" for Hillary Clinton?

Early in September, the Times was declaring Ohio (see http://www.nytimes.com/2016/09/07/us/politics/donald-trump-ohio-john-kasich.html?_r=0 ) to be "an essential swing state," where the "paper of record" gleefully reported Gov. John Kasich threatened to destroy Donald Trump's presidential hopes by withholding his endorsement and denying Trump use of his voter turnout machine.

The Times added: "No candidate since 1960 has made it to the White House without winning Ohio. And while Mrs. Clinton could afford to lose there given her advantage in other battlegrounds like Virginia and Colorado, Ohio is a must-win for Mr. Trump."