Few things on the "get excited" and other factors i've noticed about players and how it impacts their play.
1. Rank doesn't matter in tournament play. Well ofc higher ranked player is excpected to win, but that isn't 100% true all the time.
2. Cokiness. "I don't need to practise since I play only 5* maps", seen it happen, no point in excplaining further why the guy went 0-2 in groupstage.
3. Confidence is good... aslong as you don't go overboard with it and turn it into cokiness.
4. Mappool randomness, I've seen lots and lots of good players fail because "mappool had too easy maps" or "I dont play AR7 ever", thats what the tournament is for, finding the best OVERALL player. Not the fastest one, not the best streamer.
5. Preparing opponent vise. This is a bit harder task to do in a 2 day tournament when you get to know your opponents 1day-15mins before the match, but i had a player in one of my earlier tournaments who could EASILY upset his group by quickly scouting through their plays and banning what was their best/picking what was their worst.
6. N E V E R G I V E U P. Dropping combo doesn't mean you can't win, always play to the end, maybe he fails or something.