Well, I had hoped that the picture graphs would be sufficient, rather than a wordy explanation. But considering your reply, I'm not sure....
The trend since 2010, has obviously been a massive slowing of the traditionally faster indoor surface.
In 2010 as I pointed out above, conditions were genuinely fast (48 CPR). Some players complained it was too fast - Nalbandian said it was like an ice skating rink.
They slowed it some in 2011 (to 41 - Med Fast), and then since 2012, where they changed the surface to match the O2's, they slowed it down drastically, reaching clay like slowness last year (<30). Many players complained it was too slow.
This year, they finally reversed the muddying trend, and sped it up to a medium pace.
Furthermore, it appears there may be a correspondence to the conditions over these years, and the players that excelled, but that is up to the interpreters of the data to conclude.
I'm happy that the ATP has released this data for this tournament, but It's too bad the public has not been given more complete actual CPR data over the years for all tournaments, but then the ATP/ITF have never been known for their transparency. I personally think it should be publicly posted for every tournament (adjusted for weather).
Respectfully,
masterclass