I was in a unique position at the championships last season: being employed by the UPA to follow the action and write daily recaps on the website's results page for the Open Division. In this capacity I witnessed part of each game Chain was involved in, and as they progressed through the tournament I got to watch how they were able to attack so effectively against the other top teams.
First of all, they like to huck it. Obvious right? Each team I spoke with talked about trying (and failing) to stop their hucks and force them to work the disc underneath. The players I spoke with said things like, "We're gonna make 'em play small ball," or, "We're going to look to poach deep off the weak side cutters," or, "We're going to stop hucks with our straight up marks," or, as one captain said, "We're just going to back 'em, plain and simple." The problem with all of these strategies was in the assumption that Chain would be "worse" at working it underneath.
Teams seemed to start out forcing Chain back toward the disc, or "making them throw a lot of passes" in the beginning of the game. Chain handled this style of defense without batting an eye, and was content to take under cuts all the way up to the sideline. When you are throwing to players like Zip, Dylan, AJ, Wooten, Wilson, Cricket, etc., they are not going to be beaten back to this disc if they're being played honest (forget about it if you're backing them). Once Chain had gotten to within 10 or 15 yards of the goal line the defense would have to play honest, allowing Chain to dump, swing and score on consecutive throws just like that. I rarely witnessed them struggle on the end zone line, and Chain scored quickly with frightening efficiency.
So the Chain offense has now shown that it can score without issue if the defense plays against the huck. This becomes demoralizing. At some point during the game the defense would have to try something different, i.e. fronting down field, or changing your mark strategy. Now all of a sudden the deep space opens up, and hucks are being launched by experienced, strong throwers to some of the best receivers in Ultimate.
Chain's offense proved to be incredibly adaptable. They could score in a number of ways, and intelligently took advantage of teams that tried to take away the huck from the beginning. Chain played it cool at first, and proved that they could score without throwing long. Then, when the opportunity presented itself, they unleashed the beast.
On top of this, Chain's defense was incredible after the turn. The O unit's defense shown during the weekend, consistently forcing turnovers and giving themselves more opportunities to score. Credit their grit, and refusal to give up any break.