The striker had just returned from Belgrade having undergone revolutionary hamstring treatment involving horse placenta, making him a doubt for the squad at all.
Still, the Brazil-born Spain international was named in Simeone's starting XI before having to be replaced after just nine minutes with an injury, leading to questions about whether it was foolish to start an unfit player in such an important match.
"It wasn't a mistake," Filipe Luis, 28, told ESPN Brasil. "Diego Costa was feeling well and he suffered an injury in a different place. It had nothing to with how he was feeling before.
"He's our best player and having him on the pitch for two minutes was better than not having him at all."
As for ultimately losing out on club football's most prestigious award following a spectacular campaign, the Atletico defender felt that his side just ran out of steam in the closing stages.
"It hurts," the left back continued. "But we've had a very good season. We won La Liga and everyone wanted to lift the Champions League too, but Real Madrid played a great game.
"We didn't have the strength to fight back when it got to extra time. They deserved it in the end, we can only congratulate them."