A nice graphic from Business Insider on Vegas over/under for 2015 wins (with comparison to last season). To note, the top teams are projected to slip downward by a few games while some lower teams may edge up.
The Padres look to improve by 7 wins. The White Sox win 8 more games. The Cubs may win 9 more games. But the Red Sox appear to make the biggest gain with +14 wins.