Basically, the Twins didn't see him capable of contributing in the 2018 season at this point. A lot of the arms were give this looksee by the new management, and the other reality is WHY do you protect a lot of bullpen arms (maybe Jake Reed should've been the exception) if "failed" starters can be just as valuable out of the pen. What it kinda shows is that current powers-that-be kinda disagree with the direction the former regime took in drafting relief pitchers.
Stewart will need to prove himself out of the gate at AA ball to see if he can get a callup, at some point, to AAA. But in the scheme of things, he stats behind Jorge, Romero, Gonsalves, Thorpe and Littell. And there are a couple of other names that may pass him.
If no one claims him, he has to show life or go thru the whole process again. Another team MIGHT just draft him because of the investment the Twins made. But you do have to weigh him against any and all other Rule 5 choices out there. The decision is someone worth holding onto in a re-build process, or someone who has a better chance of cracking the major league roster in 2018, if not 2019 fer sure.
My only complaint in all of this is that the guys THE TWINS DIDN'T PROTECT were all valuable tradechips during the summer, then...and how many could've been packaged for, say, a Verlander...instead of placing them in minor league limbo and destroying their trade value as any team can grab them for the Rule 5? Of course, some do have trade value if another team thinks a lowly team may snatch them, and they want them and have the 40-man space.
Wasn't it just yesterday that the Twins future bullpen looked to be Reed, Melotakis, Chargois, Burdi, maybe Zack Jones, possibly Mike Cederoth...and di I leave out a prospect name or two? Was going to be hard-throwing, strikeout heavy crew, too. Instead, we have...Hildenberger, Curtiss. Moya, Busenitz, Hackimer, Jay and possibly one of the Anderson guys.