The back-row was handed the captaincy just hours before kick-off after skipper Andrew Coombs failed to recover from a virus - and he praised his team's battling effort.
He said: "It was all about us and our attitude and I think the Ospreys will agree that we fought for 80 minutes. One of the biggest things for us is going out there with a big intent to play and to dig in and not give up.
"We knew the challenge ahead, we got embarrassed at the Liberty at the start of the season and it was a really big game for us to come out and perform,
"They potentially underestimated us and I don't blame them because of our recent results and they would have seen us as an opportunity to get a bonus point.
"They threw everything at us for the first 30-minutes but we managed to ride it out - it did take a lot out of us but we can see that they fatigued as well.
"If we'd had more composure, executed things better and played in their half a bit more then we could have got something out of it as well. But they're a quality side and they know how to win games."
Evans paid tribute to the impact of the Dragons' Welsh youngsters, and he thinks that their Millennium Stadium outing will stand his side in good stead.
He said: "Tyler Morgan is a class-act, Hallam Amos showed his potential and the two second-rows who are 23 and 24 played against two vastly experienced opponents and they fronted up really well.
"It was a learning curve for a lot of the boys and it was my first game here as well - it was a massive experience and I enjoyed every minute of it. But it's unfortunate we couldn't get the win or the bonus point in the end."