Atletico have undergone a significant transformation since finishing 11 points behind LaLiga champions Barcelona last season.
Among the replacements are Marcos Llorente, Kieran Trippier, Mario Hermoso, Hector Herrera and Joao Felix, who became the fourth most expensive signing in history when he arrived from Benfica for €126million.
The level of investment, which has brought eight new additions in total, has prompted conjecture about whether the squad could be the strongest assembled under Simeone.
"It's not fair to talk about a team that is yet to start competing," Simeone said.
"We think about now, which is to improve in training, in matches, for each player to fulfil his function.
"When the season ends we will be able to say if this is the best squad or not. You don't win with names. You win with performance and with players who interpret what the team needs."