The problem lies in what you define as "a good coach". Richard in a previous post, rightly said the first sign of madness is doing the same things and expecting different results.
One only has to look at the technique issues surrounding the batting and the bowling at National level to realise that those coaching beneath this level locally, are unable to develop players fully and correctly.
Australia has 22 million people, South Africa 48 million, England 51 million yet produce world class and title winning players under the current systems. Bangladesh has a population of 161 million and does not.
That is not a criticism, it is a starting point to realising where the issues might be with local coaching.
I will be honest with you. Level 1 coaching badge is a waste of time and Level 2 is not at all difficult to pass. It is quite rare for people to fail Level 2 unless they are utterly incompetent.
This brings me back to my point of what do you define as a good coach? How is the criteria to be judged?
The problem for Bangladeshi coaches is that they may have other issues to contend with such as lack of funding, logistics, favouritism as well as simply wishing to retain control over what they do. No one likes to see overseas coaches come in and take all the best jobs. This can lead to jealousy, anger as well as a feeling of rejection. But the truth is that the history of Bangladesh Cricket at the levels beneath national/academy are the result of local coaching. It means, as we all know, that national coaches have to also try and bring players up to the right standard WHILST they are in the national team - something that just does not really happen in the other 8 Test playing countries.
I feel coach education is a massive issue in Bangladesh right now, and that a national plan should be set in place, as we have in England with Sky Sports, whereby coaches are encouraged to come forward and be educated properly and to a national standard that is measured and managed. It is only by having cricket educated players being fed into the national teams that Bangladesh will be able to get off the bottom rung of the ladder at Test level.
I think this is partially the reason 50 overs cricket and T20 is so popular. You can have less skills relative to Test Cricket and be more competitive. It's why we see associates causing upsets, but we don't witness massive upsets at test level between teams. Those rankings accurately reflect the quality of each side.
The answer then?
Make a national consensus for coaching and agree a minimum standard of coach for each level. Educate, educate and educate the coaches to be able to deliver a cohesive action plan that finds, identifies, creates and develops talented players.
There will always be the odd local coach who is very good. But given the size of the population and the fact that cricket in the national sport, with full Governmental support, Bangladesh should be awash with talent - both on the playing field and in the nets, practice facilities and clubs - just as it is in India, Pakistan and Sri Lanka
"No matter what anybody says this guy (Mushy) is THE WORST captain ever" - night_wolf