While I think the Green Bay Packers are sound tacklers on defense, Pro Football Focus runs down the list of missed tackles and doesn't single out any Packer as an exceptional tackler. But it does mention two former starters as two of the worst tacklers over the past three seasons. I doubt either name is a surprise.
LB Brady Poppinga. He's still with the team and being paid a lot more ($2.4 million in 2010) then you might expect. He's only started 4 games over the past two seasons (39 starts from 2006 to 2008), but the coaches have thought very highly of him in the past. He's coming off a season ending injury, but he was very reliable over his first five seasons. If the Packers did want to save money they could consider releasing him, but I think that shows their regard for him that I haven't read any talk of it.
S Aaron Rouse. GM Ted Thompson doesn't make rash roster decisions, even a bust like RT Allen Barbre was given one more training camp to prove himself, but they made an exception for Rouse after a disastrous start against the Bengals in 2009.