I think the key words are "Good teams". The Twins are not a good team right now. They should be in rebuilding mode, however, they seem to think they can contend and, therefore, bring up guys like Matty G. who they think can help them win now. The front office knows that the longer they appear to be in contention, the more tickets they sell. I think this move was made because of short term goals rather than keeping an eye on the long term. As Nick states, on a rebuilding team, you can use that 25th spot to stash a rule 5 guy for the future or use it to develop a prospect. On a good team, that 25th spot is often used for an aging junk ball pitcher who can eat some innings in games where a team is on the wrong end of a blowout. Terry Mulholland filled that role in the glory years. On this team, bringing up Guerrier makes very little sense if the focus is on the long term.