Striker Morata is, as revealed by Goal, expected to depart Stamford Bridge before the transfer window closes after the Premier League club brought in Gonzalo Higuain on loan from Juventus.
Chelsea boss Maurizio Sarri confirmed this week that Morata informed the club last month that he wanted to leave, just 18 months on from his £60 million ($78m) arrival from Real Madrid.
Indeed, the former Madrid player and head coach thinks Morata should have stayed at the Santiago Bernabeu.
"I'm surprised by Morata's arrival at Atleti," he told Onda Cero. "I don't know if they're the team for him. I think Morata was wrong to leave Madrid. He didn't have patience."
Schuster was speaking after Madrid beat Girona 4-2 in the Copa del Rey on Thursday, fighting back from 1-0 down thanks to goals from Lucas Vazquez, Karim Benzema and two from Sergio Ramos.
Marcelo, whose future has been the subject of recent speculation, set up Ramos to score Madrid's crucial third goal after having failed to track Antony Lozano for Girona's seventh-minute opener.
Schuster accused Marcelo this week of getting "fat easily" when he does not play, but he praised the Brazil international's impact.
"Bringing in Marcelo was very positive, although he is still not at 100 per cent, which showed in Girona's first goal," he said. "But you have to put him in. He has to play. He's an indisputable first-choice."
However, Schuster is in no doubt that Madrid are suffering from the loss of Cristiano Ronaldo, who left for Juventus in a €112m (£97m/$127m) deal last year.
"What they miss at Madrid is a player who gets 45-50 goals," he added.