Messi ran just 1.5Km more than Pinto. And half what Koke ran. That surely shows something.
Pep's Barça was built around possession + suffocating pressure to win back the ball and regain possession. This is a team full of talented players, top-class passers that need the ball to execute. These guys are 5+ years older now, they can't push the same crazy, obnoxious way they did in the past. It's either you give way to the next generation, or you change your style.
Atleti is built around Simeone's mentality, which goes back to his days with Sevilla under Bilardo: do whatever it takes to win the ball, win every clash, pressure every move, never rest. If you work twice as hard as the best teams, you may get the same chances to win. And it's working: leading in La Liga, unbeaten in the Champions League, lost Spanish Cup semis against Real Madrid on their only weak game... Played Barcelona five times this season, lost none of those games. Their only shortcoming is that they clearly depend on scoring first. If they concede an early goal they have to fight twice as hard as they usually do, and they may run out of gas early.
I see Atlético having an infinite amount of faith in their system and their coach now. They destroyed AC Milan, dominated Barcelona, reached the first UCL semis in 40years, are the current holders of the Spanish Cup, two UEFA cups in the past years, and commanding La Liga. I don't see my team (Real Madrid) making it to the final this year. Therefore I'd love to see Atleti lift the trophy they deserved back in '74 vs Bayern and get their place in history. Much lesser teams have won the UCL, now its their time.