Lambert saw his side, with an average age of less than 24, take another step forward by holding in-form Stoke to a goalless draw at Villa Park and extend their own unbeaten run to four matches.
Lambert said: "When they go out there to play, I trust them. Some of the football we're playing has been very good. But I was also delighted with the way we coped with Stoke's strength. It is hard to keep Stoke at bay with the way they play."
He added: "I was asked before the game how we would combat that and I think we used our strengths by playing football. I thought we were excellent.
"When I came here, I knew be it would be a long-term thing and that's what we're trying to do.
"We are trying to fix it really quickly and sometimes you need that time together.
"But I am not just putting them out there to learn. I know they can handle it and the last few weeks we've been very good."
More experienced defences than that at Villa have been unable to contain Stoke's threat in the air and from set-pieces.
But Lambert said: "You look at the three of them, all young lads, and I thought they coped really well against a physical front-line that Stoke have got.
"Playing three at the back is something we think will benefit us and the players have adapted brilliantly to it and are playing with a lot of confidence at the moment."