So - my two frustrations were inconsistency between games and teammates who seem to willfully neglect game objectives. It doesn't sound like anyone else has experienced these things first hand. I'm not even going to pretend that I'm a top player, because I'm not one. I have plenty of room for improvement. I realize that, and armed with that knowledge was still having difficulty reconciling the two frustrations I mentioned.
Thanks for the responses.
Anybody else who shows up is welcome to tell me how I should be playing differently, but I was more interested in what else is happening here. While "you are not the best" is accurate feedback, I don't feel it explains what I'm describing very well.
You really can't do anything about teammates other than pick up their slack, but they may be doing something else, like zoning, or may feel unsafe even if they are safe. I've seen more the opposite problem where teammates rush down the objective and get crushed.
I haven't been inconsistent very often in my games, I've only heard a lot from inconsistent players. Most of them do wholly blame their team, and to your credit, you aren't doing that, and are being very polite and looking for ways to improve. What inconsistency means is that something in your playstyle is getting very variable results and should be phased out, likely something that gets very good results if the other team doesn't know how to deal with it. these tactics, whatever they may be, are likely to further fail you as you move up in the game.
it's really hard to see precisely what you may be doing wrong without seeing you play. All of the advice I could give is really just a guess and a suggestion to things you may want to look out for. I think it's some overextending because you shut people out some games and get smashed in others, which is something I see a lot with overextending players, or players that play away from their team aggressively (the two often go hand in hand). You may also be trying to flank very often when opponents are not distracted by the rest of your team or something else, which will get you countered, pushed away, and even killed very often by aware opponents. In either cases, you need to be able to sift out bad opportunities for good ones, even if that means taking a step back for a moment.
It could always just be your weapon choice being poor in some matches compared to others, depending on what opponents pick. In that case there's not much you can really do other than take up another weapon and use both, which may help you do more consistently in the long term.