Sorry mate, but you're a bit wrong here. He really looked decent in the few minutes he got when he played for Chelsea, but being a young player under Mourinho meant that he was never going to be given a fair chance.
Brandt is a good young player, but doesn't have the pace and directness we need in the side, which Salah would provide. In terms of depth and squad balance, we need a direct speedy winger as we currently only have Mane in that position, and not a left or right sided midfield technician, which Coutinho or Lallana can both operate in.
Also, we faffed around over a few million at the time, or Ayre tried to low ball Basel, after which Chelsea swooped in, offered their asking price and offered better terms to the player causing the deal to fall flat. Hardly am indictment on the player, more so on our management at the time.