But the one thing I found really pretty unbelievable was Harry Kim becoming the new Security Chief. Promote him yes, but leave him at Ops. There was nothing in the series that ever made him out to be a tactican or a fighter, so where did that come from?
The same could be said of Chekov yet apperently he was the Enterprise-A security chief.
Upon returning to the 23rd century, Chekov and his shipmates faced court martial for their actions. However, they were eventually cleared of all charges and Chekov was reassigned as second officer, navigator and security chief on the USS Enterprise-A. (Star Trek IV: The Voyage Home)
Just a guess but this is probably one of the reasons why the author got the idea to make Kim security chief of Voyager.