A flagellum, like other biological structures, serves a function for the organism, and has too many parts to be explainable by a single genetic mutation, so natural selection must have played a role in its development.

So it's the pattern of the flagellum that needs explaining, because it's orderly. In what way can the flagellum, or pretty much any other biological structure of interest, be said to be orderly though? In the case of planets, solar systems, crystals, etc, we can tell that they're orderly because we see the same simple pattern being repeated over and over again, so we eliminate chance and conclude that there's a basic common law behind it. But the flagellum is not orderly in that same fashion. It's a heterogeneous structure, so to speak. That is, you can't produce the pattern that needs explaining by repeating a simple algorithm over and over. Something about the flagellum stands out and seems orderly, but what is it? In what way can it be said to be orderly, such that a better explanation than pure chance is necessary?

There are statistical reasons why passwords and encryption schemes work to resist chance intrusions into a computer system. It is essentially the same body of mathematics that Dembski used to make his arguments. The formalisms are nasty (like a good legal document), but the concept is fundamentally simple even though, as Dembski aptly shows, the mathematical formalism are horrendous.

We create passwords knowing there is a degree of improbability that someone else can use random chance to arrive at the pattern in our head. So far so good. The mathematics are hopefully straight forward. If someone breaks your password, you can calculate the likelihood it was due to a random accident of some monkey on a keyboard accidentally logging in as you!

Less obvious is that we humans have (for whatever reason) collections of universally recognized "passwords" in our heads. This is very obvious as illustrated by the following experiment:

I tell students to take two shoe boxes with about 30 coins in each box, and then randomly shake one box, and build an obvious design in the other with the intent of persuading a future onlooker that one of the boxes has a configuration of designed coins.

The experiment has a very high success rate, but the reasons why are not so obvious. Students can invariable build designs which other students will recognize as designed. They are in effect sending a "message" in their design. Walter ReMine's Biotic Message theory is essentially saying biotic reality is one such message from one intelligence (the Intelligent Designer) to another intelligence (us).

Essentially, there are conventions, idiosyncracies, universal "passwords" through which humans can communicate design to one another in physical object like coins, and if need be, even molecules. See:
IBM written in Molecules

There are probabilities associated with these universal "passwords" or human-like idiosyncracies appearing through random chance alone.

Dembski showed that natural selection is even worse than random chance at creating these human-like idiosyncracies in physical objects, thus effectively destroying the claim that some sort of "chance plus natural selection" can form these idiosyncracies in physical objects better than random chance alone.

If one defines naturalism as composed of laws that are:

1. deterministic
2. stochasitc
3. some combination of 2 and 3

Dembki showed that all three will fail to account for the appearance of human-like idiosyncracies in physical objects. It is not an argument from ignorance, but a "proof by contradiction".

Reailize, that 1,2,3 can not account for why your passwords can not be broken by anything except an intelligent act. By way of simple extention, the appeance of "universal passwords" or "human-like idiosyncracies" in physical objects can not be attributable to 1,2,3 either.

Indeed, if one believes in the many universes theory that there are an infinite number of universes, and if there was no law of gravity, then there certainly would be universes that have their matter arranged by chance to appear is if there is a law of gravity. In fact there would be an infinite number of such universes. The many universes theory completely wipes out an surety of any kind that we might propose and come to accept by elimination.