I disagree with you. Our OL is a total mess, picking Fashanu would fix it, although we would need to upgrade with at least one other lineman via trade / draft or FA signing. He is a generational type player.
The line is a mess when it's not healthy and they are putting guys like McDermott and Lowe out there at tackle but it's a lot better when they are healthy. Brown and Onwenu are both good tackles, Andrews is the leader of the line and Sow has played well since moving back to guard.
If the team had more talent on the offensive side of the ball, i would agree with you and Fashanu might be the consensus choice if they miss out on the top 3. Get a younger and more reliable option than Brown. When your qb sucks, your best wr is either a 6th round rookie or Kendrick Bourne who has a torn acl and your best tight end is a guy who's probably just outside the top 10 for the position, you take either one of the two best qb prospects or a great wr or te prospect like Harrison or Bowers if they are on the board, even Nabers would be more of a need if they are picking 5th. Detroit have three first round picks on their line but they are a good team because of that talent they now have on offense.