The Russians are playing games up near Alaska also, Buzzing a B52 a few days ago!
They actually have tailed or flew alongside a B52 several times this year. Getting close enough to see pilots and insignias, which is not something that typically happens. Seems they've been pushing to find where the limits are, or just to show they're not afraid to shake things up a bit. They have done that several times over the years.
Airspeed is typically lost during a dogfight, and depending on the maneuvers, a lot can be lost. Nothing says that they couldn't have been playing the same games with your Air Force pilots. No pilot is going to shoot a missile without a direct order from above, and that's not likely because nobody wants to start an international incident, but that doesn't stop games from being played. I'd find it a bit odd that it was over land, but they have been showing aggression, like you said. So who knows...
Just ended a 25.5 year run, flew reconnaissance for most of it, until I went to strategic stuff in 2014. You are right, the Russian shit is all political, as any military operation is, including war, just a means of politics. BTW it's as much internal nationalism as ity is flexing muscles. I'd call your assessment spot-on for "why" As a mostly-career recon guy, I have been chased by them all LOL
As far as the airspeed, yes of course airspeed is lost, dogfighting is primarily outperforming and out-thinking the adversary (or multiple), one of those variables that applies to both is airspeed management. Dogfighting skills were ID'd as one of the biggest shortfalls after the Vietnam War and the MiGs, which caused the USAF to adapt gunnery and tactics school into the USAF Fighter Weapons School and the Navy to create Top Gun (real name USN Weapons School) I graduated from USAF WS in 2000 and taught there from 2002 - 2005.
I do not see a power stall, vertical stall, or Cobra maneuver being anything other than acro, sure it can be thought of as out-thinking, but in reality, you have no flight controls in a stall, you are counting on some differential engine control and gravity, and finally, remember, you don't go right back to "going fast". You sort of hang like an apple on a string for a while as the other guy is raping around a turn coming back for a fight with a throttle full of hate.
Now, maybe that's not what he saw, hard to see from the ground without binoculars. BTW, interesting history, when the USAF WS started, they would assess the trainees and even assist by sitting on the ridgeline in Nevada and watching the fight by binoculars and talking on radios. US military has come a long way
The fight certainly is 3-dimensional though and the vertical is a great place to live, especially if you have a thrust to weight ratio that you can accelerate, but often it gets confused for a video game. It would be interesting to know what he saw. One of the things to realize though is that it could have easily been blue on blue. A lot of the FSU countries still have Russian equipment. Could have been a absolutely friendly training mission