"You can interrupt an overhaul under the circumstances," Loew told an online news conference. "In the defence we did not have the desired stability recently and... experience may have been missing in some games."
"Mats is a player who influences other players and brings experience," Loew added, also praising Mueller's superb season with Bayern Munich.
Moenchengladbach, who have lost all seven games since it was confirmed Marco Rose will leave to coach Dortmund next season, can end their dire run at bottom side Schalke on Saturday.
The 17-year-old became the youngest English scorer in the Champions League when he netted for Bayern in Tuesday's 4-1 last 16 first leg win over Lazio in Rome.
I thought about it a lot but at the end I listened to the feeling that it is the right decision to play for Germany.