The start of a new baseball season represents hope and optimism, the ever-present possibility that this will be the year that ends with a champagne celebration and a parade through the streets.

At least, that’s what it’s supposed to mean. But as the 2018 campaign gets under way this weekend, the number-crunchers in Las Vegas see things a little differently. In their minds, it might as well already be time to fast forward to October.

The...