Great Britain's run of tour defeats shows the team has "gone backwards", says head coach Wayne Bennett, halting the progress made since he took over as England coach in 2016.
The Lions have largely been comprised of England players used by Bennett during his four-year tenure.
Saturday's 23-8 defeat by New Zealand in their second Test meeting stretched the tourists' winless run to three.
"We're not adhering to the things we need to do," Bennett told BBC Sport.
"I feel tonight and since we've been here that we are getting away from it [the game plan and the skill levels].
"That was what we were doing when I first came in as coach in 2016, we tidied some things up in 2017 and 2018.
"The disappointing thing for me is we've gone backwards a little bit."
He continued: "They were trying hard and panicking a bit. They probably lost their way a little bit, so I'm not going to be over-critical at them for that.
"You play differently when you're playing catch-up - you're under more pressure. But I can't fault their effort. That's always been tremendous and nothing was different tonight."
Bennett's future as England coach is still uncertain, with the Australian's existing contract set to expire at the end of the Great Britain tour.
"That's a decision they (the Rugby Football League) have got to make," he said. "My contract finishes next week so we'll see what they want to do."
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New Zealand Warriors coach Justin Morgan, who is working as a pundit for BBC Sport, said: "They made a number of unforced errors.
"You are going to make errors in rugby league and you can handle forced ones.
"A couple of times when they had some good field position in the first half, Great Britain didn't build any pressure through the kicking game.
"In the second half the ball didn't go to the right players enough, it needs to go to the halves and there were too many sets where it went to the props."
All part of the preparation, says Bennett
It will not please fans who place great importance on the return of such a prestigious and historic brand as the 'Great Britain Rugby League Lions', but Bennett has seen the tour as an extension of his plans for an England Test series with Australia in 2020 and, further ahead, the 2021 World Cup.
His squad selection featured just two players to have represented another home nation rather than England, in Ireland cap Joe Philbin and Australia-born Scotland full-back Lachlan Coote.
The side which took to the field for the Kiwi Test solely comprised England-qualified players, including playmaker Blake Austin on the wing and back-rower Jack Hughes at centre.
There were also some notable omissions, such as injured 2018 Golden Boot winner Tommy Makinson, experienced captain Sean O'Loughlin and now retired back-rower Sam Burgess.
"It is about 2020 and 2021 with those two years featuring Australia Tests and the World Cup," Bennett added. "I've been doing a bit of experimenting here, we'll see what we can do.
"We have a stronger squad now, when I get them all back and they're all fit, than when I started in 2016 so that's important and we just need to get our football back on track."
Despite the result and the adversity, captain James Graham is confident the team is moving in the right direction before the final Test of the tour against Papua New Guinea on 16 November.
"It's been a big test this week," Graham said. "We've had a number of injuries, the squad has been tested and players have played out of position but no-one has complained.
"We've just got on with it within the group, we were confident as a group with the lads coming in.
"There were a lot of debutants throughout the series and a lot of lads can be proud of the way they've come into the group."