The downside on them is their schedule is brutal. @TB, @WAS, WAS, PHI, @ATL is a brutal first 13 games.
Now that I look at their schedule a bit closer, I'd probably take the under on 27.5. They only get 14 games against teams under .500 and then 6 more against the Phils who finished right there and are also improved this year.
On another note, the Orioles schedule is just brutal. After the first week (which includes their only four games against Miami), they get Tampa (3), Yankees (3), @Nationals (3), @Phillies (3), Nationals (3). Later in the season, they play 11 straight against New York (alternating between the Mets and Yankees) then get the Braves and Tampa after that for an 18 game stretch. I'm honestly surprised they get an over/under of 20.5.
This would true under any scenario that has them as a major league team this year.