The sight of three Rovers playing staying up the pitch when their side was defending a corner.
Under previous boss Darren Moore Rovers would rarely leave any players close to the half way line in such circumstances.
And Butler explained it was designed to force visitors Portsmouth into a tough decision over whether to look to make the set piece count or guard against a potential Rovers break.
“Paul Gerrard and myself spoke about it and just thought why not?” he said.
“If we defend the ball well, then we’ve got three players up the pitch. They will sometimes have to leave four back and if they don’t they’re susceptible to the counter attack.
“You’re playing cat and mouse with the opposition.
“One week it might work, the next week it might not.
“It’s about moving forward and not standing still and becoming predictable.”