Aside from Bill Shatner's acting(or over-the-top acting - depending on your point of view), Morgan Woodward also did an excellent job in playing the ill-fated Captain Tracey. Near the end of the episode, you could tell that Tracey had really gone over the edge(i.e. the scene where he disintergrated McCoy's scanner that Spock jury-rigged to contact the Enterprise).
The way he was ranting and raving of how the Yangs sacrificed so many of their own, just to draw the Kohms out into the open, it was clearly obvious that the loss of his ship and his entire crew, let alone him being unable to prevent such a disaster, just made him snap. And worse, his situation on Omega IV thereafter, before Jim Kirk and his crew found him.
Clearly, battle intoxication(mixed with mental instability)had set in, causing Ron to have a severe nervous breakdown.
Even though Ron Tracey was a direct opposite of Woodward's other character(Simon Van Gelder from Dagger Of The Mind), Tracey was still an interesting character and one of Woodward's finest performances.