I will say this about rubs and competitions and running a business as well.
Spices are like the Colombian Coke market.
A). Rubs are made of Spices
B). with the exception of Salt and Sugar spices are better some years than others. Anyone that mixes a batch of rub up every month (say 15 pounds or more at a time) will notice that some spices may be more colorful than others even when in the same bottles.
C). Spice Companies Often Cut their Products with inert Ingredients or OLD outdated spices.
And don't think I don't do this in my Business. I will cut an old batch with new after I compare.
D) Companies that make Rubs for your BBQ ALSO do this from time to time. Not everybody but some do.
E). Even when everything is perfect Mother Nature can affect the base product. Peppers are the most affected.
So lets review... If you make up your own batch, you have mother nature that is trying to screw you, the original spice farmer that cuts his product, any middle men who cut their product (often with outdated Spice), the Spice Company itself and the company that makes the rub.
The closer you are to the source the better. No that does not mean buy it yourself but Mixing it yourself would help.
Sadly, those that buy someone else's Rub are at the mercy of whoever mixed it, bagged the base spices and farmed it, and of course Mother Nature. Sad thing is, by the time you notice it... its on the Judges Table.
Make your own rub (even if you are stealing their recipe). Control it! I ask you, would you prep those chickens, pop them in the smoker and let some stranger tend the fire while you go watch Jenna Haze in Taste of a woman? No! Why control everything then sprinkle on the most important element of taste and leave that to chance. This is why I think some competitors win with simple ingredients - because they control a few simple things instead of hoping 13 spices get their groove on correctly.
How did we get into this trap of using Rubs and Injections? The BUSINESS of BBQ, baby. You can sell a bottle of crap and make someone think they are going to achieve the same results some champion did a lot easier than have that champion explain his technique.
Of course any brethren that sells his product here at this forum... I am not talking about you.