Saturday's 2-0 win at struggling Elche marked the champions' fifth consecutive win in all competition, while Simeone's men have also only failed to triumph in one of their previous 11 games.
Mandzukic has seemingly hit form too, with the Croatian scoring his eighth goal in nine matches on Saturday and his sixth in La Liga in 2014-15.
And Simeone does not believe it is a coincidence that Atletico are impressing at the same time as Mandzukic is finding his stride.
"The team have played differently for several matches and we are growing," he told reporters.
"It's no coincidence that Mandzukic has had many chances and the team are doing well.
"The talents we have are making great effort to continue competing. I made 10 changes [from the Copa del Rey win over L'Hospitalet] and we still competed. That's good for Atletico Madrid."
