Pinnacle used to allow this until about a month ago, I don't even look to bet totals anywhere but Pinnacle.
There is some correlation.Take a pitcher like a Pedro, Randy, etc, say he is -200. If you want the dog, I believe it's good to parlay it over ( usually very low number ). The stud pitcher is likely to be off his game, if he loses, give up more runs than normal, thus leading to an over. I do this a lot, the payoffs are nice, you can get +400 or so in spots.