It looked like Crutchlow might be ruled out of his home MotoGP round by injuries from a practice crash for a second straight year after an accident on Saturday morning left the Briton with ankle damage and sidelined him for qualifying.
But he was given medical approval to ride in the race and charged from the back to sixth.
"That was a truly incredible race and words almost fail me to describe the job that Cal did today," said Poncharal. "We weren't even sure this morning that he could ride, so for him to finish in the top six is a result I don't think we expected or will ever forget."
Crutchlow's charge culminated with a last-lap move on Nicky Hayden's Ducati.
"We thought he might be able to get close to the top 10 but obviously once the adrenaline kicked in and he felt his confidence coming back, he got his head down and we were happy when he got seventh," said Poncharal.
"He was a long way behind Nicky but to pass him on the last lap sums Cal up perfectly. He never gives up, he's got amazing self-belief and he has got a lot of guts to match his talent. I am proud of him and I'm sure all of the British fans are too."
Crutchlow said the final result was far better than he had anticipated.
"I never imagined I could get sixth position because normally if you start from the third row it is very difficult to get into that position," he said. "So starting from the back of the grid, I'd have been happy to finish the last prototype bike.
"It was a very tough race but I just had to try and ignore the pain and let the adrenaline and support of the British crowd get me through."
He reckoned the performance proved that a maiden MotoGP podium on home ground would have been achievable without the Saturday crash.
"I'm really happy with my lap times because I was as quick as the guys on the podium, even with a broken ankle," said Crutchlow. "So a little part of me can't help but think without the crash that I could have been on the podium in the British Grand Prix."
Crutchlow was keen to praise his crew - "who basically chose the set-up of the bike for me and it worked great" - and the British fans.
"When I was lying in the gravel yesterday all I could think was they weren't going to see me ride in my home race again," he said. "Their support helped me a lot and I hope they went home proud of the job I did for them."