They also had to fix the hitters....they had zero, zero, starting pitching prospects to work with from before they took over. They have Ober and Varland. They have SWR. They have Jax and Duran. They've traded part of the pipeline for Gray (but I guess turning the 18th pick into two above average years doesn't count).
I'll ask again, how many pitchers do you expect them to develop (and not count good trades at all)? This idea that we should only judge their ability to get pitching by the pipeline, and only the pipeline, is off to me. YMMV, of course. But these comments are, at best, veiled criticisms of their ability to build a staff, IMO. And, they ignore the trades (not all of which are good, but TB traded Ryan, do we say that proves they are a bad FO?).
Your suggesting the Twins pipeline hasn't been as good as the best team in the league at doing it? Agreed, so far. But, if that's your bar for success, I think it likely you are disappointed. Just as judging them against TB (the only team able to do what they do) will disappoint others.