Is Atletico still in their cup tourney? They could use him as a back up and rest Costa for cup games now that it's the crucial part of the CL. And they're just two points behind Barca at La Liga too.
Atletico were kicked out from cup by Girona last week. Costa is injured now, but until injury he scored only 2 goals this season. So, now they usually they have Correa and Griezmann in atack. They also have Kalinic, but he rarely plays full match. I think that Atleti need to improve their attack, but I'm not sure that Morata is better than Costa or Kalinic.