The Borussia Dortmund defender was part of the team as the nation's defence of the world title came to a crashing halt in the group stages but feels things are different this time - even if they face a tough group that includes France and Portugal.
Hummels told Kicker: "At that time, we had the problem that we had not yet found each other as a team, neither in the training sessions before nor in the game itself.
"That will certainly not happen to us against France. It mustn't happen to us again to lose sight of the team. I can honestly say the feeling now is different than it was back then.
"Everyone wants to become a unit, everyone is ready to sacrifice themselves for the team. We can go far. We are on the right track; we know that we have the skills to win this tournament."
Hummels spent two years in exile from the national team after the World Cup embarrassment in Russia but admits that he had no doubt to return when asked by coach Joachim Low.
He said: "We never had a problem with each other personally.
"In terms of sport, the views were different - but that's quite normal in sport. There are always different opinions. I was rather sad because I always enjoyed playing for Germany.
"We talked about [a return] for the first time a few months ago. From that moment it was clear to me: If he wants me there, I'll be there."