Poppinga contributed most significantly to the 2005 season with his high-energy play as a coverage man on special teams plays, posting a team-high 22 special teams tackles through the Packers' first 13 contests. Though Poppinga never started at linebacker in 2005, he saw more and more playing time through the season due both to injuries suffered by the starting players and because of his ability as a pass-rusher. This special pass-rushing role played to Poppinga's strengths and allowed him to post two sacks during the 2005 season. His best single-game performance was an October 23 contest against Minnesota, in which he accumulated five tackles (3 solo) and one sack of Vikings quarterback Daunte Culpepper.