What we have here is a wave. This wave represents the large amount of new players/toons that arrive and progress through the world of warcraft. The theory that I created is that the wave of new toons will progress through different stages of farming roughly at the same time. This ends up creating a shortage and a surplus of mats throughout the level stages. In my example i am using the leather market.
The Wave of players has now reached heavy leather, and like light leather, it lowers the price to 5g a stack. My example is in the time frame right after the large amount of levelers pass heavy leather. As you can see Borean Leather is around 10g a stack (where it was before cataclysm's release along with all of the other leathers). You can also see that Light Leather has settle out to around 35-40g a stack which I will explain towards the end.
So we've learned that "C" is the players leveling/farming and "A" is the wave itself or the increase in price after "C" has passed. "D" represents the calm before the storm... all of the new toons don't have a need for borean leather yet, nor are they able to farm it, so it remains the price that wrath left it. "B" is what i call the wave trail its the time when there are only a few stragglers left leveling and farming. Nobody wants to back track and farm old stuff so the price settles relatively high for the people who are willing to buy there profession levels. I call this inflation, because what happened was, the wealth of WoW increased from factors such as more 80 quest rewards/gold. So the 80's that were doing their quests instead of leveling a new toon. well they have now created a new toon and began leveling, they have a lot of money from the new quests they completed and they want to catch up with the wave so they buy their way through professions.
So say I invest 100g into light leather. whats worth more money now, initial 100g investment in leather or just 100g? The correct answer is leather. The inflation increased prices and i now have gold that i wouldn't have had if i hadent invested.
Now I said for the example that all the leather was 10g at the end of cataclysm. all you have to do is plug in the current price of whatever mat and use roughly the same ratio, the graph will turn out the same.
The very last thing is that cataclysm's arrival would in theory increase the price of borean leather for people to level as cheap as possible, well all you have to do is picture this as 2 waves one at the start (light leather) one at the end (borean leather). those 2 waves moving at the same pace and you have now learned "The Wave Theory"
by Xeroaze from tippedcopper.blogspot.com