[quote="http://pastebin.com/gEYvZNEz":1337]PP is based on relative skill. The harder the map, and the better your play on it, the more pp you gain. The pp that you gain from a play on a map is the 'raw' pp. This 'raw' pp is the same as Tillerino tells you that you would get.
Now, for the sake of explaining this, let's say the raw pp is 50pp. That play gets in your top ranks, and is then weighted against all your other top ranks. And you would get for example 35 'weighted' pp. So you didn't gain 50 pp, and were never meant to.
Furthermore, because that play is in your top ranks, and is weighted, everything below is now weighted less than before. Meaning that you gained 35pp, and then lost Y pp because of everything below it now being worth less. Which makes you effectively gain a small amount of pp (for example 1 - 10) instead of the 'full pot'.This explains more than I can, but if you have any questions feel free to follow up!
Also, next time please ask in
here. All osu! related questions go there.