I'll start off by saying that it's been a pretty remarkable team turnaround. I think all three phases have played better. Not that they aren't without their flaws, but definitely better. When you get contributions from all three phases, it makes the other look good. The defense getting a turnover gives a short field to the offense. The offense having long sustained drives help the defense. Special teams helps with the field position and hitting FGs makes the long drives count for something.
Having said that, I will go with the man who's head we were calling for just a few games into the season, Jack Del Rio. The entire defense has turned it around and they are winning first and foremost with defense. There are some players that have stepped up, Jamin Davis being at the top of that list, but the unit as a whole has been great these last 6 games. I'll give credit to Del Rio and his defensive coaches for getting the whole unit to play well.