The Twins won't be putting their best twenty five players on the Opening Day roster. That's never quite how it happens. Instead, much of how the final few roster spots are decided comes down to how the players fit into specific roles or whether or not a guy can be sent down to the minors without risk of losing him.
The Rule 5 Draft, one of the most obscure and convoluted things in all of sports, can give players what equates to a golden ticket into the big leagues. The Twins ended up with Justin Haley once the dust settled on this year's draft (it's a long story), meaning they get to keep him just so long as he's on the 25-man roster (or the DL). Haley comes over from the Red Sox, where he put up very similar 2016 numbers to another recent Twins acquisition.
Player A: 3.14 ERA, 1.121 WHIP, 8.6 K/9, 2.0 BB/9, opponents hit .241/.286/.366
Player B: 3.01 ERA, 1.118 WHIP, 7.7 K/9, 2.8 BB/9, opponents hit .225/.291/.345
Player A is Adalberto Mejia, Player B is Haley. Mejia is the better prospect because he's two years younger, but Haley's probably a better bet to be of use to the Twins in 2017. Also, one big advantage to a Rule 5 draftee is development gets tossed out the window. The Twins wouldn't want to use Mejia as a long reliever because it would derail his development as a starting pitcher. With Haley, they can't send him to the minors for further seasoning as a starter. It's now or never.