A couple of friends of mine have this website called the MLB Price Machine. It uses a very complex, very detailed set of statistics to spit out a projected line for every game. Once the lines are released at the offshores, they go through and see how much the lines are off from their projections. They call this percentage the "Calculated Edge". Then, they post their plays, beginning with a minimum 10% calculated edge.
It's a really helpful tool for getting the best number. That's what the ultimate goal is - to get the most value. So far this season, they've been able to get an addition $745.91 worth of value by jumping on the opening lines instead of getting the closing number. In total, they're 322-336 on plays, but are +17.31 units. So, if you followed every one of their plays with a $100 bet, you'd be up over $1700. That's a return on investment of 2.32%.
Check it out. They've put a ton of work into this and aren't getting near the respect and notoriety that they should be.