Peak bumrah is current, not past. By 2023 after injury not only was he an improved bowler but people started comparing him to atg legends and top 5 best bowlers ever, Before that no one thought he was the best.
Indian fans hyped him in the same way they hyped Gill at one point to be the successor to kohli and rohit and that fell flat and similarly they hyped rahul at one point, But international fans just viewed him as a solid prospect with a funny action.
It was only after injury where it became apparent that this guy is the greatest pacer India has ever had.
As for Ishant, Ishant is overhyped sorry to say, Siraj and shami were peak at that time period though I agree.
Also which series are you talking about? Classic Australia beat 2004 india in their own den? Every series they had Australia mostly won besides one off games where india won? And one off games happen, 2017 india was >>>>>>>>> Pakistan but lost by 180 runs simply because it wasn't their day that day?
Also classic india isn't as weak as people think, their batting is superior to modern era and even Kohli's india. Dravid, Sehwag, Sachin and Laxman are terrific players and its laughable to think that pujara or rahul compare