A Mikel Gonzalez own goal and Antoine Griezmann's close-range strike inside 10 minutes helped Atletico to a sixth clean sheet in seven matches.
Atletico - renowned for their defensive strength - have conceded just one goal in their past seven matches. Only Barcelona (17) and Valencia (22) have allowed less goals than Atletico (23) this season.
"For sure, being strong defensively has been our structure of these years," Simeone said post-game.
"Going back to being strong defensively speaks highly of all the staff, of the whole group. Because it is not only the defence, it starts from the forwards and the better the forwards work, the better the defensive work is.
"Let's see if we can continue on this line that is hard in the face of so much competition."
Atletico's return to form defensively has seen the club embark on a seven-match unbeaten streak in La Liga, with the Madrid club in control of third position thanks to a quick-fire start at Vicente Calderon.
The home side benefited from some misfortune early on after Gonzalez headed Koke's second-minute corner into his own net.
Atletico doubled their lead eight minutes later thanks to Griezmann, who got the better of his former club, with the France international producing a composed finish to beat goalkeeper Geronimo Rulli.
"I must interpret that the team comes out very strong and settles the game like that," Simeone added.
"Today's second half was played better, with better ball game, with better possessions to keep the game going. The team found the goal and at least today we could hold the ball much better."
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