It's not even mediocre at this point really. And there aren't many teams that have some sort of secret sauce in terms of development. For the most part it's about volume. Drafting 20 pitchers isn't desperation. It's just a mathematical oddity. My guess is that they didn't skip over 9 position players higher on their board to take Ky Bush. How does adding a sprinkling of position players in that draft really change things all that much.
By and large, there's no magic to keeping your farm system decent. The angel's biggest problem has come from self evaluation. They either don't know who they are or are unwilling to accept it. For about the last 15 years they have not moved some players when they had an opportunity, they've prioritized proximity to the majors over talent, and they've traded away org currency where the return, while fair, wasn't close to moving the needle (making these efforts wasted).
On top of that, their starting point was scorched earth so there was an entire infrastructure that needed to be repaired. Even putting a solid foundation in place doesn't do anything when you don't have building materials.
Another thing that's hurt is taking that year to year win now philosophy to free agency. Instead of turning 1-2 years contracts into prospects at the deadline with good players, it was making multi year commitments to high priced players that became immediately un moveable. Which in turn limited your financial resources. And because that need to field a competitive team was pervasive, any extra money was spent on 'lightning in a bottle' types with low odds of having any value that could turn into futures.
Finally, the recent emphasis on getting your highest value picks to the major as soon as possible contributes.
Teams do each of these things sparingly based on the situation, and while none of them are individually catastrophic, doing them all, across the board, every time, over a period of 15 years, has resulted in exactly where they are now.
the next problem is that now there is a solid core of young players at the major league level with zero support elsewhere in the org. In order to take advantage of that, they'll justify their deadline deals of, again, taking talent close to the majors over more worthwhile players who would take time to develop. And while the FA market was pretty thin this last year, a decrease in payroll was favored over adding some mid range talent that could be swapped for future talent at the deadline.
The bottom line is that they're still doing it the same way. A general unwillingness to accept a plan that requires 5+ years instead of less than 3.