I was planning on writing about this earlier and I noticed sdpads24 wrote about it in the comments, but let's get a little more in depth about it.
Last night was the first time this season that Shawne Merriman was back on the sidelines with his teammates. We all know that Merriman is the emotional leader of the defense and always leads the defense in the pre-game "physce up". He has mentionend on the radio @ KIOZ 105.3 that when a player makes a bad play or whatnot he is usually the one to tell them what they did wrong, how to fix it, and encourage him to do better. (as an aside, Shawne always does interview's on 105.3 every monday morning on the Mikey Show, and also Wednesday's @ 6 pm).
We all saw that last night was our most complete game, and the best performance of the season from our defense. So the question is, Does simply the presence of Shawne Merriman on the sideline improve our team, especially the defense? Of course, we need to be careful not to confuse causation with correlation and other such logical fallacies. But the emotional boost of the leader being on the field behind you and backing you could be making a huge difference.