Cubs at +550 (Olympic) to win the division seems like a line worth at least a small play. If either Houston or St. Louis would start to open up a lead, an offsetting play on them could be made that would allow you to at least break-even.

Or if the Cubs get off to a nice start as they did in New York, the lines on the other contenders should go up enough that some money could be made no matter who ultimately wins the division.