I found Irish to be the worst character in a game I played in 2013.
I don't know why game writers always have to portray military characters to be such brutish, unlikeable assholes at all times, as if that is somehow normal. One of my greatest takeaways from my time in the military is the friendships and relationships I formed with my fellow Marines. Our camaraderie was really all we had to get us through combat, games should focus on that. Everyone in BF4 is just angry, all the time. It's draining.
Spec Ops: The Line at least had some of that, they tried to explore the tense, but respectful relationship of the soldiers put into an intense environment. There was at least some kind of feeling of authenticity to the characters, they kind of felt and acted the way real people would act. Medal of Honor 2010 even has a bit of that, with mixed results (but infinitely better than what BF3/4 or MoH: Warfighter did).
Battlefield 4's characters all fucking hate each other, and it's difficult to take seriously. The game tries to glorify them, but it comes off so disingenuous and distasteful. The writers just took the "serious all the time, only way to communicate is by yelling at the top of your lungs" stereotype and cranked it up to 11, and it feels so laughable and absurd. The dialogue is just so bad. Just so, so bad. They just didn't even try.
Or maybe they just tried to make Irish a symbolic character to show what alcoholism can do to a person.