You are still yet to provide evidence for why this sudden, worldwide collapse in fast bowling stocks occurred. Until you do, my theory is the only one that is actually complete.
Unlike your brand of doomer, everything to do with cricket was better in 1820 snark, I'm pretty open to being proven wrong here, but all I'm getting is results based analysis like what Zebra posted above.
No one here is disputing the results between 2000-2010 were bad. I am putting forward a theory as to why they were bad. I'll even give you there is room for a small decline in talent, but the total collapse in results cannot be explained by a historical blip in talent in my view.
Imagine being a fast bowling coach and explaining to your national board CEO that you no longer have any good pace bowlers because all the pace bowlers are just inherently bad? He'd throw you off the 10th floor for failing to do your job - turning talented young men into world class pace bowlers.
The fandom and media in this sport is pretty incredible* in that if this thread was about batsmen, everyone would acknowledge 2000s batsmen benefited from motorways, helmets, modern bats and whatever else quite happily to (correctly) contribute to the argument for ranking Miandad above MoYo. Make the same thread about bowlers and it wasn't that they ran into a perfect storm of new challenges, they were just bad.
*dumb
You've repeated yourself without addressing the fact your theory doesn't address the quality of bowlers
coming into tests. Why is it hard to accept that there is simply variation? There is probably not a single reason across each country or even in each country. You're talking about a group only about 30 people at any one time, not more than a handful of which will be absolutely top flight.
Let's break it down looking at the fast bowling dependent countries:
Australia: We had decent depth in the late 80s/early 90s with McDermott and Hughes, but McGrath was the first top flight bowler since Lawson's good spell in the early eighties. From then on the bowling was centered around him. Gillespie was good across both decades but the mid/late 90s support cast (Reiffel, Fleming) was a bit more capable than the overlapping one to the mid 00s (Lee, Bichel, Kasprowicz). Clark emerged to redress this but didn't stay for long and then it's the frustrating Siddle/Hilfenhaus/Johnson era. Overall after McGrath there was a little less immediate quality in the 00s. Even then our average only increases from 26.65 to 27.74.
Pakistan: the closest there was to a successor to Wasim and Waqar was Shoaib, who was injured all the time. Asif emerged but had his own issues and was banned when he was really starting to hit his stride. Pakistan's pace bowling quality was contained in only two bowlers and when they went, their penetrativeness went. Average increased from 25.82 to 33.34.
South Africa: never produced a successor to Donald, Ntini was nowhere near the same level and Pollock gradually faded as his pace declined. No one else had any staying power until Steyn got it right, Nel being the next most prolific. Philander took a long time to catch the selectors' eyes (he made his FC debut in
2004 and had taken a lot of wickets when finally picked). Average increased from 25.61 to 28.95.
West Indies: as dependent on Ambrose and Walsh as Pakistan were on the two Ws. Bishop aside no-one was better than meh and the pace torrent (based largely around one team, Barbados) was a trickle even by the mid-90s. Guys like King or Rose looked promising but didn't kick on for one reason or another. Everyone else was tosh. Average goes from 26.39 to 35.68.
England: remained pretty much the same mix of condition-dependent good-but-not-greats and promising players who get injured. Their average actually improved from 32.85 to 31.7 from the 90s to the 00s.
Won't bother about the others.
The vast majority of the change was that WI and Pakistan went from really good to crap when their top flight bowlers (a grand total of just
four) retired, Aus and SA got worse but not as dramatically, England improved slightly. All this was discernible simply by looking at who was playing (eyes, not spreadsheets). Why did the changes occur? Pakistan has never had any depth. WIs well dried, while pitches did get slower there but the drying happened before that, with the last very good bowler being Bishop from
1989. Aus and SA might well have just experienced natural variation. But the fact is all these were set in stone before anyone ever stepped onto a test pitch, flat or not.
And add that Australia had the batting equivalent of WI's pace factory in the late 90s to the mid 00s, and India managed to put together a far deeper and more powerful batting lineup than they ever had before. We they perhaps advantaged by flatter pitches the 00s? Maybe, but they all entered the international game well before then. In any conditions I'd back the batting from both teams to be better than their 1990 equivalents.
Part of the issue here is the confusion to distributions. If top class bowlers were randomly distributed we'd expect peaks and troughs of bowling quality,
because random is not uniform. Certainly there are cases where conditions have affected certain bowling styles. It's visible all the time for spin, and for pace India and Pakistan post-War and Australia in mid-late sixties are both clear examples where poor pitches impacted fast bowling stocks. But your 21-24 averaging bowlers are so rare simple natural variation can be powerful.
Did fast bowling get worse in the 00s regardless of other factors? Yes, in my opinion. Did batting get better in the 00s regardless of other factors? Yes, in my opinion. Were
test pitches flatter in the 00s? Yes, in my opinion. Can these things reinforce each other to produce an observable change? Yes I think, the 00s were higher scoring. But are they foundationally dependent on each other? No. You can ask whether flatter pitches in country caused changes at domestic level which spilled over into tests. But flat test pitches cannot be responsible for the fact that the bowlers debuting on them aren't as good.