Stevens has not been in a matchday squad since mid-January, but Lambert puts the Irish rookie's absence down to the improved form of Joe Bennett at left-back.
"I think in the last few games he's been excellent, Joe, I really do," said Lambert. "He's starting to look like the lad we wanted to bring.
"I think the last few weeks he's been right on top of his game. He can definitely deliver the ball. There's been some big tests for him lately, but I think he coped very well with it.
"Because of the way the team's been performing you can only pick so many lads, so at the minute there are people ahead of him, but he's been training well and doing everything that we've asked of him.
"I thought he played excellently against Manchester United that day, but you've just got to bide your time."