His figures from 10 years ago would only get him top 20.
A peak Chris Froome today would have better training, recovery, nutrition and equipment. Ergo better figures.
Or, his training, recovery, nutrition and equipment (just about) were cutting edge 10 years ago and everyone else has caught up now, while he might not have that much more to improve.
I'm reminded a little of a classic ting about Danish riders up until about ten years ago - they were thought to be really good jnrs, but not able to develop more when they got to senior ranks - the theory was that their advantage was good coaching early on, so they maximised their potential earlier. Froome may have just got his polish before the rest did
I'm dubious by these riders who claim better numbers than ever before. I think they're just trying to give themselves comfort. I don't think it's a coincidence that riders who were at the top of their game but had serious crashes never quite managed to get back to the top of their game.
I think there's something in that, but then again, Vingegaard smashed the record he held jointly with Pog for the Tourmalet from '23 - but didn't smash it by as much as Pogacar did, so who knows?
As for the whole average speed question, I think there's a risk we're comparing apples with bananas. The Tour hasn't just been raced faster, it's been raced differently. With TV from the start of every stage they've reduced long sprint transfer stages, and with GC fights breaking out on any mur type finish or steep Cat 3 a few km from the end even the rolling days for breakaways have become controlled. Breakaway riders have been chancing their luck a bit more, and the fight for the break has been far more strenuous. Once a break has formed it's been kept very tight, so nobody can relax and enjoy a day off.
Obviously that also requires a peloton in tip-top form, with all those nutrition and training advances and super lightweight aero bikes (noticed how they ride aero on mountain stages now, because the weight penalty had been reduced for aero frames?)
That's what takes the average speed up, not 30" shaved of an HC climb here and there.