It's late and I am lazy to do a search, but in my recollection break-point I think was Japan; first race Hembery said they will deliver harder (?) tire. I cannot provide you with actual data, but intent about change was announced on the internet. That much I do remember; to what degree tires changed I cannot say, but you are also correct in stating that also almost all teams understand operating temp. range much better, yet not all teams managing that window successfully, however improved as season progressed.
If you have a news report that says otherwise I'm happy to be wrong, but I'm pretty sure each compound is exactly as it was at the start of the season. What's changed is that the teams understanding (and skill) has increased. They have learned and improved.
Edited by Sakae, 27 October 2012 - 17:56.