The point of the rebuild is to rebuild the entire roster. There’s zero guarantee that one player (Tua) will single-handedly change the franchise. He very well might, as he seems to have the potential, but no one knows for sure. Ask Ryan Leaf about potential, or JaMarcus Russell, or Vince Young, or Sam Bradford, or Rick Mirer, or Akili Smith...
The season and the draft will unfold the way it wants to unfold. Just sit back and enjoy the ride. If they win, great. If they lose, oh well. None of us knows for certain how a college player will play in the NFL. If people really knew for absolute certain, then we’d have to start multiple threads about all the lottery winners posting here.