The rotation was already better than they had been given credit for
Sure, the Twins don't have a lot of sexy names and signings like we saw this offseason. There isn't a Max Scherzer, Justin Verlander, Jacob deGrom, or Carlos Rodon type of addition to this staff in 2023. Normally, if we saw a team in the bottom third of the league jump into the top 2-3 staffs, you would expect to be able to say "wow, signing THAT guy made a big difference" but that isn't really the case here.
Granted, the Twins did trade for Pablo Lopez and sign him to an extension and yes, he has been excellent so far in 2023. However, it is probably just true that the Twins' rotation was better than folks initially gave them credit for. Sonny Gray has been consistently good for a long time now and Joe Ryan has always had the arm talent and fastball to succeed and we are just seeing that come to fruition now.
Even with sub-par starts and injuries for Tyler Mahle and Kenta Maeda, having three guys at the top of rotation and a guy like Simeon Woods Richardson as depth to cover innings while Mahle and Maeda get healthy portends good things going forward.
There is room for more out of this staff
There is also always the factor that a staff is maxed out in terms of their upside and production and there may be parts of that happening here in all fairness. It is probably safe to assume that Sonny Gray isn't going to average 1.4 fWAR every month this season as sweet as that would be. Every guy on this staff is going to have their ups and downs...that is just the nature of the game.
However, it sure seems like there are some places where the Twins could get even better. Kenta Maeda and Tyler Mahle were meh to even bad before they both went down with injuries in the last week or so and from the looks of things, neither of those injuries appear to be serious. When healthy, both of those guys are just strictly better than how they have thrown so far in 2023.
The bullpen's production has also been pretty medium (in terms of fWAR) outside of Griffin Jax and Jorge Lopez. If Jhoan Duran cuts his walk rate down, he may become one of the better relievers in the entire league and give the bullpen a big boost all on its own. In short, this is a group that hasn't reached its ceiling yet and that is exciting.
In short, anything can and will happen over the course of a long season and the Twins are no exception. Maybe these injuries to Maeda and Mahle prove to be more troublesome than currently thought. Maybe another key pitcher gets hurt or forgets where the strike zone is. Maybe Griffin Jax comes back down to earth or Duran's issues with walks start biting him more.
On the whole, though, this Minnesota pitching staff looks very good and looks like they could stay that way for the long haul.