The Austrian internationals noted that they don’t know what has gotten into the Portuguese superstar.
Rangnick came under heavy criticism from the Manchester United forward during an explosive interview with Piers Morgan.
The former United interim boss was described as ‘not a coach’ by Ronaldo, who didn’t hold anything back in the interview.
The 64-year-old spent six months as an interim boss before he was replaced by Erik ten Hag last summer.
Rangick was named as the new Austrian boss before he departed Old Trafford but Ronaldo revealed that he was shocked that the unknown manager was named as United manager.
Austrian stars defend Rangnick
In a swift reaction, midfielders, Schlager and Baumgartner have come to the defence of Rangnick, who they described as successful.
“I don’t know Cristiano Ronaldo personally. I have no idea what got into him there,” Schlager told the Austrian newspaper per Der Standard via TalkSport.
“Everyone knows how much influence [Rangnick] had in Austria, at RB Leipzig and also in Salzburg.
“He was successful everywhere. He is a very great professional who has also changed football a bit.”
On his part, Baumgartner added that the former United boss had already proven himself to be a great success in Germany.
“He has also had great success as a coach,” he added. “That’s where Cristiano Ronaldo’s frustration comes from.”
The 37-year-old Ronaldo has since joined up with his country Portugal to kick off preparations for the 2022 FIFA World Cup.