Everyone here who has seen my work in baseball the last 10 years knows that I will never bet a game +1.5 runs. How can you possibly bet on a team to lose by exactly 1? That is my rationale.
WITH THAT SAID, some of the most successful baseball bettors in the world, specifically QT comes to mind (although he's getting buried this season) have made millions taking +1.5 runs. Pinnacle's own office is largely responsible for pumping up all of these big favorites so they can go in toward post and take out all the +1.5 at better numbers. These are not idiots doing this, but merely some of the best gamblers (read - sports investors) in the whole world just getting the best of it math-wise.
More times than not, the math supports that -1.5 is a bad play and +1.5 is a good one if the markets were dealt on a man-to-man exchange. With the books juicing both sides properly, the players should always be up against it no matter which way they go but inevitably the +1.5 is a better bet because mostly suckers lay 1.5 (and suckers have a large share of the baseball market especially when laying big numbers). Hence, you see the syndicate money come in on +1.5 after the game gets either driven up by the suckers or pinny, englishman et al phoney the game up even higher than it should be to begin with.