Manti Te'o was a great player, but on paper the Fighting Irish have the linebackers to replace him. The problem is that as great as he was, the defense is not missing the player but the leader. Comparing the performance against Michigan this year compared to last. Te'o had the game of his life with 3 interceptions and he raised the game of all the players around him. The players all tackled well last year and now this year this same group is missing those tackles. That can't be a coincidence.
It reminds me of what happened about 8 years ago when Brady Quinn graduated. He was the heartbeat of that team that had a great offense that went to two straight BCS bowls. When he left, the offense was so inept that they took about 4 games before they scored a touchdown. The team went 3-9 that year.
Now I don't think Notre Dame goes 3-9 this year as there are some differences. All of Quinn's weapons such as Jeff Samarjidza and Darius Walker all left too. This time there is still a lot of veteran players on that defense such as Louis Nix, Stephen Tuitt, Dan Fox, and Carlo Calabrese. One of them needs to become that leader. Being a leader is not something you can just do though. It has to be in your personality. I am hoping one of those guys takes that roll like now.
Another guy that might have to take on more of that role is Tommy Rees. I know he is not on defense but the quarterback is generally the leader of the whole team. Tom Brady, Peyton Manning, Ray Lewis, and even Te'o last year have been known to inspire the whole team.
Getting back to the question, it made a difference when Quinn left and the Indianapolis Colts won two games the year Manning was hurt. Look at the Baltimore Ravens also. They went from Super Bowl champs to getting demolished on opening night without Lewis.
Notre Dame's defense is clearly not the same without Te'o. They got manhandled against Michigan and they honestly didn't even play that great against Temple despite only giving up six points. The bottom line is that somebody needs to step up and be the face of this team. If it is not from the defense, then Rees or possibly TJ Jones needs to step up and be that face.