I've used the same model for the past few seasons including this one, and the number of plays has been decreasing every year. I have a play when my line/total is way above/below what it's set at. My totals plays decreased 24% from 2012 to 2013, and projected to drop another 18% this year. ML's have decreased too, though not as much as total plays. only about 5% a year drop in plays. Vegas must be either getting better at setting the totals, or however they model is coming up with a number too close to mine to be profitable for me.
MLB has definitely become more sharp. LT Profits is a good example. For about 5 years, he cleaned up on MLB, then last year he did terribly, and he is struggling, this year. A lot of sharps lost money last year on MLB. You can still win at the sport, but isn't going to be nearly as easy as it was in the past.