Repeating your falsified points, like Grandpa Simpson does his stories, doesn't make them any more interesting, Migara. To reject them again:
1) "Bradman dented averages more than others..." True!

Congratulations. Vastly and uniquely too.
2) "It was 0.72 which is meagre": False and false. It is 1.28. Which is vast. So much so it elevates the 30s decadal av above 4 other decades. Take DGB out and the 30s fall 4 places to 2nd lowest. No one else in the game's history can claim such an impact. Even if you replace his stats with another Hammond the 30s stays 2nd lowest. But in reality you wouldn't do that. You'd replace him with a fringe player who averaged about 30 and would have no impact on the decadal ave.
3) Then followed some genaralised blather abt DGB not facing guys like Marshall, Hadlee or Warne: Irrelevant. Neither did SRT face Roberts, Holding, Garner or Croft. Besides you don't know. Your comment is a simple colour (generational) bias. For eg if Hadlee played in the 30s he'd have played 8 tests as an unlikely maximum; and your prejudice wouldnot be allowed to concede Hadlee's greatness due to the small no. of games he played!

Therefore you rate opportunity NOT skill. Skill is revealed by stats. The stats show the 30s bowlers to be easily superior to the 05 English ashes winners. They are equivalent to Eng's bowlers of the 50s. Your bias has placed you in the unenviable position of effectively arguing that Trueman and Statham can't bowl...good luck with that without looking stupid.
4) "If DGB dented bowling ave's by 4-5 runs, others must have benefitted bowling at him otherwise his impact on the decadal ave wouldn't be 1.26". This statement neatly explains your ignorance. The 4-5 run figure refers to DGB's impact on
individual BOWLING aves. On a selected, but representative group, he did inflate averages by atleast that many. The 1.26 figure refers to impact his 1.8% of innings had on the
decadal BATTING ave. That is his 1.8% of innings had such an impact on the 98.2% played by others it elevated the entire decade's batting ave by 4 places which is unprecented in the game's history. Do you understand now that the 2 points are compatible, not contradictory?
5) "If a bowler concedes 31 to DGB.." STOP! No bowler I know of got off that lightly. The 10 best English bowlers DGB faced conceded 76 runs on av to him. The remainder paid around 150 runs for each Bradman dismissal! (5 cont) "...with a batsmen averaging 0 against the same bowlers it brings the av down..." Joke!

The accumulation of other batsmen these bowlers faced include Woodfull, Ponsford, McCabe, Jackson, Kippax, Fingleton, Brown and Hassett. None of them averaged 0 against these bowlers and wouldn't have lasted if they did. The fact you even raised this point proves again the confusion in your mind that you can't distinguish the difference btwn an impact of individual bowling aves versus the impact on the decadal batting ave.
6) "Decadal aves in the 30s are just ashes averages...50-75% were ashes games". True but only to an extent. I don't know the actual % of ashes tests but they are the majority though not the only games played. But this means the best and greatest players played more often and thereby distorted the decadal ave moreso than any other era. That is why Hammond's impact on the 30s ave is 4(x) greater than SRT's impact on the 90s ave despite the similarity in their personal aves. Bcos, proportionally speaking Hammond played 4(x) as often. So if the 30s had as many bad players and teams as the 90s, and had them playing more often, the decadal batting ave would fall even further. Providing even greater statistical confrontation for your prejudice against that era's bowling to bear.
Bcos you don't get that point you don't get the importance of the disproportionately high no of their decade's innings DGB and Hammond played. Yes that is down to circumstances. Its a distortion that can't be repeated in modern eras.
But it has the real impact of inflating the decadal batting ave. Whereas the preponderance of crap modern players distort batting aves down,
generally flattering the bowlers of the modern eras. So its far from a 2 way street. The inbuilt bias flows almost one way and in favour of the modern era.