It all comes down the math, I just posted an example of the formula in a message called Tell me How, by Certain death (not duplicating a post). But basically the higher your Delta the more likely you'll win, but not a given.)
Also remember the randomizer is based on either the user's or the server's CPU (Unknown which) so if it's bogged down some very unexpected outcomes may be likely. I would expect "Luck Burst" when, if it's server based traffic is high, and when you have alot of apps running if it's client based.
I would bet it's server based or a hybrid client/server based (where both client randoms are sent to server and highest random number wins on the server then sent back to client).