Well unless there's been an IPC regression from Ryzen 2, it's gotta be 4.6 GHz or less. Also, unless IPC has improved by more than 15% it's gotta be 4.0 GHz or more.
There isn't an IPC regression, we already know that. AMD won't claim an IPC gain, which they categorically have, then provide a regression.
Second, look at 65 v 95W Ryzen now, what's the biggest difference, lower base clocks and much lower all core boosts.
https://www.computerbase.de/2018-04/amd-ryzen-2000-test/6/
If you go down to the table near the bottom they are showing average clocks of various chips in the left column, the left number is clocks under 4 threads and the right number clocks under full load. A 95W 2700x has 4.13Ghz under 4 threads and 4.05Ghz under full load.
The 65W 2700 has 3.85Ghz under 4 thread but only 3.35Ghz under full load. That's the difference the 30W makes. The chip being used, regardless of what the clocks are supposed to be, will maintain FAR lower clocks than a 95W 8 core would under the same circumstances, pretty much 20% lower. 65W chips have a pretty huge difference between rated turbo speed and actual all core fully loaded clocks.
As for ES's and guessing how far downclocked they are, there is no point and bringing up past models is pointless. One generation ES chips might be at 70% of final clocks, another they might be at 98%.
Remember these are the same chiplets that are going to ship in EPYC Rome chips which it sounds like they might be shipping as early as in the next month or two for direct to customer sales.
Timeline isn't official but it seems like Q1 is AMD selling Rome direct to the likes of Google/MS/Facebook/massive data centres. End of Q2/early Q3 is desktop and Q3 is Rome to people like Dell selling smaller numbers of servers in the way they do. In other words the 'ES' chips now should be pretty much finalised for server and sure desktop is higher clocks, but the silicon is still pretty much finalised.
ES samples can be whatever you want them to be, there is no set rule that they are massively downclocked, they are only downclocked as far as they feel the need to make them for the people they give them to.