England winger Ryan Hall's second-half hat-trick was in vain as the Stobart Super League champions suffered a hiccup in their build-up to next month's Challenge Cup final. Wakefield, who had already lost twice to their arch rivals this season, led 18-4 at the break.
They thoroughly deserved to make it third-time lucky after outscoring their visitors by seven tries to four and McDermott said: "Wakefield came out of the blocks a lot better. They were gifted field position from some errors from us. A bit of ill-discipline early gave them that field position which created the tries."
Leeds clearly missed the creativity of suspended half-back Danny McGuire, while Brett Delaney, Carl Ablett and Ryan Bailey were also absent from their likely Wembley line-up, but McDermott did not hide behind the absences.
"We didn't have our best team out there, but the team that was out there was more than good enough to beat Wakefield had we managed the game a lot better," he said.
"Credit to Wakefield, they didn't let that happen. We missed the blokes that weren't in the team, but that's not why we lost."
Leeds threatened to turn the game on its head when Hall twice collected Kevin Sinfield's kicks to the corner early in the second half to haul his side back into contention, but Wakefield finished the stronger team.
Wildcats coach Richard Agar said: "I think we were creating chances right through the game. The worry for us was that we let a couple of opportunities slip and we know there is no better team at posting quick back-to-back tries.
"Their first try came from an intercept but we didn't go into our shell and for the second successive week defended all right. I thought defensively we were pretty good and we played some entertaining football.
"The key was that we played to our strengths. One of our goals if we can't make the play-offs was to be a good, competitive team and we've showed that we're a handful for any team when we see enough of the ball."