Build a POC for every such an artifact. There should be a 1:1 mapping between the conceptional word of bubbles, arrows and boxes and the source code. If there isn't you aren't done yet.
Go through every artifact and think about whether it is really needed. Ask the question over and over again: "Do we really need it?". If there is no good answer why it exist - just remove it.And remember: Bubbles don't crash.
It was hard to tweet about it (>140 characters) :-)