Nerlens and Terence Davis, at least they can defend, Birch, and Biyombo would be upgrades.
Nerlens Noel is averaging 1 point and 3 rebs in 3 games at 14 min per, on 16% FG%. He is not the answer. Terence Davis is a wing and not even in the league right now, also not the answer and not even a need. Biyombo probably isn't any better than Queta, so I don't see him helping.
As to Birch, there was a time where I had some interest in him. There seemed to be a stretch when he was on TOR where every time I saw him play, he looked decent. Not sure the current state of his game but surprised that SAS would just waive him. Probably not a good sign.
The problem this season is similar to where we were at last season. If a player is actually going to help, they need to be better than say Brissett or Pritchard or Hauser. Just being better than Kornet doesn't help. Think when we brought in Muscala last season, he was better than Kornet and better than anything Noel or Biyombo or even Birch has done lately, but he wasn't good enough to actually help.
I don't think it makes any sense to bring in what I call a scrap heap guy, someone who is waived or who is a salary dump from another team. The move needs to be something more like the TPE and a first round pick to get an actual useful player, a player with value that takes a first round pick to get. Scrap heap FAs or useless players on bad contracts are not the answer.