Mercedes boss Ross Brawn says Michael Schumacher deserves the label as 'driver of the century' - even though his comeback did not achieve the high targets that were set.
Schumacher returned to F1 in 2010 hoping to be gunning for championship glory, but in three campaigns he has so far been fastest in qualifying once and only delivered a single podium finish.
Nevertheless, Brawn believes that Schumacher's contribution to the team and the sport should not be underestimated.
"I think he is the greatest racing driver of this century," explained Brawn at the press conference where Schumacher announced his retirement.
"I was very privileged to work with Michael from the very beginning and obviously we had some fantastic times, tough times too, but also very successful times.
"I think Michael brought a lot to the team in this second period that people don't see. There was a huge contribution behind the scenes.
"We have not achieved what we wanted to achieve together, and that is frustrating, but I think what we do achieve in the future, Michael will have made a contribution to it. So for me personally, [that is why] he is the greatest racing driver of this century."
Mercedes-Benz motorsport boss Norbert Haug was also full of praise for the way Schumacher had applied himself to the job - even though success was hard to achieve.
"He gave it everything. He never complained, and he was a constructive guy," said Haug. "I learned from this 'new' Michael in his second career even more than in the first, because he was successful and we were friends and we are friends."
Brawn said that Mercedes did discuss future plans with Schumacher - but in the end it was unable to reach an agreement because of issues over the potential length of the deal.
"Michael was well aware and kept informed, and we discussed our options with him," explained Brawn. "Michael was considering the situation, and you have to remember that if there was an agreement reached it wouldn't just be for one year, we needed a longer agreement than that.
"So it evolved as a mutual decision. It suited everyone to make the decision that we did but, of course, Lewis took some time before he made his mind up on what he wanted to do. There were no conflicts or decisions in the process, it evolved very smoothly.
"Michael kept us aware, kept me very aware of his feelings and his thoughts, and we discussed the way that decisions were going, or discussions were going, and I think the important thing for the team is someone of the calibre of Lewis does not become available every day. That was an important factor that came into it."