"Though he doesn’t think it’ll result in a trip to the injured list, Bailey Ober acknowledged knee and hip discomfort is playing a part in mechanical issues that have resulted in reduced fastball velocity" - Dan Hayes, the Athletic
I had to go look up the exact quote that was used in the article as there seems to be a game of telephone being played to separate the two issues from each other. If this quote is to be believed, then yes, he has knee AND hip discomfort AND it's affecting his mechanics. I'm no doctor, nor pretend to be, nor did I stay at a Holiday Inn last night so take my opinion for what you paid for it. I suspect that the Twins staff already know the timetable it would actually take for Ober to come back to 100% and its likely season-ending (think Topa last year or Tonkin this year). As many of us have commented, there are no more quality arms in St. Paul to bring up and I'm also suspecting that the FO also knows this but aren't willing to waive the white flag yet and put Ober on the IL or subject the pitchers in St. Paul to a task they aren't ready for yet. With that being said, Ober should be put on the IL because continually tweaking with his mechanics to match his pain level serves no one. It doesn't serve the team now and won't serve him later and will be used against him when it comes to arbitration negotiations in the upcoming offseason.
That brings us to what we should do? If my suspicion is correct and the eventual fix is some form of season-ending surgery, but Ober can pitch through it until then, I'm unsure the FO will make a change until they decide they are out of the playoff race and then he will magically have season-ending surgery. It's not uncommon for athletes to have nagging injuries that they play through that restricts their movement or their abilities. Again, using Correa's own plantar fasciitis as an example that wouldn't be fixed until after the season, but could be played through with proper treatment. I do believe this is why they signed Gillespie, to eventually take over for an IL stint from Ober or a Paddack trade as a rotation placeholder until the arms from St. Paul improves enough to be given a chance at the ML level. One final idea would be to use Adams with an opener. Difference between Adams and the pitchers they have tried the opener idea on (SWR and Festa) is that Adams is used to coming into the middle of a game as they are currently piggy backing him with Raya. Raya gets the start and Adams gets the 6-9th innings.