You should read the testimony of the only witness the prosecutor favorably quoted - claimed to police he was 100 yards away, but before the grand jury, claimed to have been 50 to 75 yards away. So it was inconsistent and he was far away, yet the prosecutor praised him for giving testimony inconsistent with many other witnesses. Witness number 10.
That is a pretty minor inconsistency and can be chalked up to a misjudgment of distance by the witness. And obviously the physical evidence (which the grand jury held in much higher regard than eyewitness testimony, and rightly so since eyewitness testimony is garbage and shouldn't even be admissible in court in my opinion) corroborated that and other witnesses' testimony within an acceptable margin of error.
I think you are putting too much weight on the eyewitness testimony and not giving proper consideration to the physical/forensic evidence, which is infinitely more reliable than any eyewitness (even officer Wilson himself). To the grand jury, the physical evidence did not show enough cause to believe any improper use of lethal force took place, regardless of what any of the witnesses, both for and against officer Wilson, may have said.
Was this handled improperly by the prosecutor? More than likely. But what I am mainly concerned with is was the right decision reached? I believe it was and so did the only people that really matter at all in this; the 12 members of the grand jury.
I also find it absolutely ridiculous that Holder is still pursuing a civil rights violation indictment against officer Wilson. Doing so elevates this circus to witch hunt levels and actually makes me question the integrity and possible racial biases of Holder. Although I am happy that most legal analysts, even the ones who think Wilson should have been indicted, feel getting that civil rights indictment will be extremely difficult since he wasn't indicted by the state and the federal government would have to show Wilson intentionally and maliciously violated Michael Brown's civil rights.