Sounds like you aren't good enough to win one and therefore rationalizing why you are performing badly during one.
I was guility of this at one point. Took over a year off and just practiced and played a small circle of regulars.
Recently, I realized I need more of a challenge. My game had became so solid, I wanted to really test myself.
In order to go to the next level in my game, tournament play is necessary. My weakness right now is stage fright, performance anxiety.
Now, when I miss, I know it is not because of lack of practice, but what is happening between my ears. Simple, unforced errors are killing me, but I know that the only way to get over this is to keep at it. I'm not used to having a crowd watch me play and that is what's is creeping into my mind at times.
The last two local handicap tourney, I went to third in both and on the winners side in both. But, I was stopped both times by the same person. A more consistent player, that has really good ball control.
When he plays, there's a crowd watching him and I just fall apart regardless how well I played getting there. He's my new bench mark.
Before, the year or so off, I would have just said its no big deal and probably stopped. Whereas now, I realize that to become a top player is a evolution, a multi-level process that takes a lifetime. Once I accepted this fact, I can take the bad play because I know this is needed in order to evolve as a pool player and as a person at the same time.
Winning is only as big a deal as you make it.