i can think of two reasons i quit betting them back in june, whether its relevant to what the pros do i couldnt tell you.
1st i rarely if ever make regular plays on anything higher than -125, and it seems more often than not they are just over that number and therefore not something i would normally include in my selection process. whether i missed winners or losers, its just outside the parameters with which i constrain myself in baseball
2nd is with all those unders any kind of run line play gets much more difficult to back so any edge in value taking them at -1.5 the risk is amplified by their own low scoring