Lillyman says they can make excuses about new players taking time to gel but concedes their problems were largely self-inflicted and the result of poor application.
"It has been well-documented we don't handle expectation too well and we're notoriously slow starters which is a pain in the backside," Lillyman told Tony Veitch on Newstalk ZB.
"There's a hell of a lot of expectation on us, we know that, and with that performance in the first half, we let a lot of people down.
"We've got a new spine and we can make excuses but it wasn't that, it was intent in tackles, it was defensive reads and technical things that let us down.
"We just weren't in the right frame of mind defensively. There was definitely a mindset shift in the second-half where we pegged back and put ourselves in a position to win it but that first half cost us."
The tone was set when five-eighth Johnson failed to find touch from a penalty in the opening minute and despite showing spirit and glimpses of their potential in an improved second half, they lacked the accuracy and mental steel to snatch the result when it was on offer.
The Warriors forwards found some muscle after halftime, with new signing James Gavet, Bodene Thompson, Sam Lisone and Simon Mannering making their presence felt, and rookie hooker Nathaniel Roache added spark off the bench.
That momentum allowed Johnson's attacking flair to come into play and three tries in eight minutes gave them some hope, before James Tedesco's second four-pointer sealed the result in the 79th minute.
"I just felt like we were waiting for someone else to do it," coach Andrew McFadden said. "And maybe that's just the combinations and where we are as a team at the moment.
"It's hard for your halves to do anything when they're not winning the physical battle. Once they started to do that, you saw what they can do.
"It's a mindset thing, just a more aggressive approach. If it wasn't for a couple of pretty poor errors at the end, we might have been able to sneak home with it."
Lillyman regrets that the defeat adds more pressure on McFadden to keep his job and said it was up to the players to alleviate that strain by bouncing back in Friday night's away match against last year's grand finalists the Brisbane Broncos at Suncorp Stadium.
"That's a real shame because he's the man to take us forward and to get the club where it belongs," he said.
"It falls on to us as a playing group to over the next few weeks get some runs on the board and try and gain some momentum."
Meanwhile, luckless second-rower Ben Henry will undergo scans to determine the severity of the leg injury that forced him out of the first half. The initial diagnosis is Henry has either dislocated the patella in his left knee or ruptured his quad.
