I'm pretty sure most people working in the league would say you're extremely pessimistic. Mantha and Svechnikov have very good chances at being top 6 players. Bertuzzi, AA, Sadowy have very good chances at being good bottom 6 players. Sheahan, Tatar, and Nyquist have all proven to be top 9 players, no matter how poorly you view them.
Sproul just had his best run as an AHL defensemen in the playoffs. XO has showed well in all of his games with the Wings. Russo had a tremendous rookie season with the Griffins. Saarijarvi looked like a Vatanen-clone in the WJC.
Mrazek has done nothing but show he can be one of the best goalies in the game at 23 years old.
We lack elite prospect talent in very specific areas - those being center and defense. Those areas can be addressed in this draft. It's also very possible some of these spare parts you've maligned exceed your lowly expectations.