D&D have done a stellar job in my opinion. I wouldn't have picked any of those guys over them. All those shows had one sub-par season too.
I'd say they've done a really bad job because they got the spirit of GRRM'a books wrong.
They have a very teenage enjoyment of the books. The only things they really cared about was the shock and the horror.
Them wanting to do the show for the Red Wedding explains a lot because ultimately they stopped caring more and more after that.
Game of Thrones went from a show that wouldn't cheat to help its heroes to cheating to help the villains.
It jumps holes in logic to make things work.
People are no longer responding realistically to things. They act how the plot dictates they act.
People teleport from one episode to the next with no clear passage of time.
We get inane unfunny scenes like putting fingers up someone's asshole and Pod the Rod etc.
Character development is now jumping from point A to Point G rather than a gradual process.
Characters are stripped of layers from their book counterparts.
The world feels a little empty.
And many plots don't feel well thought out.
I mean the show does have positives too.
The acting is great. The visuals are great. The costumes are great. The cinematography is great. And every once in a while they do get the spirit of the books right.
But the show has ultimately become popcorn entertainment. Which saddens me because GRRM'a books are very intelligent and well thought out if a little bloated.