This!
We have to admit that in many cases (if not all of them) a change for reliability reasons means a less powerful PU.
As they said it was made for the 2016 engine with their focus on what it'll be in the near furture (due to further PU frozen parts) the biggest area of development - a name here fuel and last but not least lubricants.
There is a huge potential lying under those products with all those nanoparticles which are essentially in nowadays F1 fuels and lubricants, with both benefits here in motorsport and road car industry.
Therfore they had to concentrate their efforts around combustion (chamber, pistons etc) in order to cope with a new rage of fuels and lubes.
Now you have noticed there are only 2 or 3 times a year they could introduce a new fuel, due to a 3 to 4 months need for research and extensive tests.
So here, with the introduction of their new PU, it said they are at least 6 months in advance from everyone in combustion area.
Now going back to the qualy and the race, my thoughts are the following:
1. With their WCC and WDC standings in mind they could afford an one off if their new PU fails, at least in Hamilton's case, I think;
2. Customers teams didn't afford to take those risks with an experimental PU, e.g. Williams couldn't afford to lose points and 3rd spot on WCC in a race were RB will probably pick no points. Same with FI and Lotus;
4. Where could be the ultimate test bench for a new PU other than Monza?
5. Rosberg couldn't afford to take that risk and bearing in mind he has a 6 race old PU and last but not least this is the tuffest race (on engine side) on the calendar, therefore they run it more conservative than they would have liked.
6. In some degree they took the same measure to Lewis's PU, both from the new engine perspective and looking what's happening with Rosberg's unit.
7. Something tells me Ferrari are likely to show off here, with a setup towards more to qualy and Merc do the opposite, knowing they'll have here the first row in their pocket. Prove to be a risky tactics afterwards ...
8. Maybe Ferrari did some real gains with those 3 tokens, especially with their MGU-H, were it was spoken to be down on Merc one mainly in qualy with having a non aggressive engine mapping deployment?
9. Or maybe camber and tyre pressures affected Merc cars the most?
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