Let me try to elaborate on what I meant by saying that the aforementioned players were "ill prepared". I think that each case was specific. Let first start with the goalie Kralj.
Everything you said about Kralj is true. Unfortunately, he is not a starting goalie in his club PSV. He is either 2nd or 3rd choice, but almost never the 1st. The fact that he prefers not to leave the goal-line reflects his lack of confidence and lack of development in his game which are, in my view, primarily due to very few competative games he has had since he left Partizan. In fact, the only competative game he had in the last year was the qualifying game Cro.-Yug. in Zagreb. At this stage of his professional career and with the huge talent he has, Kralj should be among top 20 goalies in Europe. Since he has been essentially a banch-wormer in his club(s) during the last 2 years, he was not adequately prepared for such a strong tournament such as EURO2000.
Mijatovic career is in slump since he left Real M. He had bad injuries which prevented him for playing more than few games for Fiorentina. His personal life, as you mentioned, just aggreviated this situation. He was not ready to be our key forward player in EURO2000, although his game, as you noted, was not that bad. I think he should have given up his position to Kezman and should have come in the game off the banch. I have a lot of respect for him and hope he will return to his old form. However, I am a bit scheptical about this. First, he is playing in Italian league where defenses, unlike in Spain, practice strict marking, giving very little space to players. This is not a good style for Mijat. Second, he is in his post prime football age and there is no more than 1-2 good years left. It will be beneficial for him to return to Spain or to go to some good Franch or Portuguese team where he would have a better chance to thrive.
Miha behaved as a dumb fool. A month-and-half before EURO2000 he was injured and did not play. As a consequence, he got some extra kg-weight, became even slower than he normally is, his shot became inacurate and his air game suffered. Frankly, without his deadly shot Miha is just a mediocre player. He needed another month of competative games to return to his standard form. Another thing that made his bad situation even worse was that Boskov's decision that Miha would be the captain was altered by the people from the football federation. This made Miha mad and disrespectful of Boskov and people from the federation. He felt that he was the most successful Yugoslav player during 1999/2000 season and that he erned the captain band. With such a state of mind and with his substandard form, Miha was not ready to play in EURO2000.