Eddie Betts, Jeff Garlett and Cameron Cloke come out of the side that put 24 goals past the Demons last week and Lappin admitted he had a bit of tinkering to do with his forward structure.
"Eddie's number two in the league for forward 50 tackles and Jeff, on average in the games he's played, rates really highly as well," Lappin said from Visy Park on Friday.
"We've taken out our two best forward 50 tacklers alongside Brendan, who'll be our best tackler this week hopefully, so that's a fair bit going out of side defensively in the front half, so hopefully the guys who come into that area can carry a bit of that slack.
"We might go a bit tall at times this week just to mix things up a bit and see what might work for us in a final if we need to go that way."
Lappin said the trio had responded well after coming to grips with the consequences of their tardiness in turning up late to the recovery session the day after the big win over Melbourne.
"They trained really well on Wednesday, but they were a bit flat earlier in the week because they know they let the side down and they were really disappointed with their actions," he said, adding none of the three was guaranteed a return for the following weekend's final.
"They've put their spot in jeopardy for the finals, but hopefully the guys who come in can really perform well and I suppose that punishment will really hurt them then."
With Richard Hadley out with a broken arm and Joe Anderson omitted, the Blues made five changes ahead of the match which will determine who and where the club plays in the first week of the finals.
Lappin agreed that number wasn't ideal at this stage of the season.
"You can't really do much about that [though]," he said. "Four of them are injury or club suspension.
"You don't like to make that many changes at this time of the year, we just want to try and settle our side down for our first finals game whoever that's against.
"Hopefully the side can do the job against Adelaide and we can get a home final."
Shaun Hampson got the nod for the second ruck spot behind Matthew Kreuzer this week which puts him in the box seat to play finals, but Lappin said the pressure applied by Robbie Warnock and Sam Jacobs had been intense.
"We just went with Shaun because he has played most of the year," he said.
"He's missed the two games [leading into this one], but he's a young athletic boy and we've really missed his work around the clearances.
"Robbie's done a terrific job at VFL level, but he's had no pre-season and no real [fitness] base to work off, so at the moment we're not willing to risk him.
"He's doing a terrific job and he keeps banging on our door and Sammy Jacobs is the same. He missed eight to 10 weeks with his injury, so both of them are a little bit underdone and haven't quite the fitness work into them that the other two boys have."
