Does the group you are playing with change anything? I notice that with some people, I have good rounds, yet with other I cannot do anything right. Unfortanately, it's my local course where some of the latter play.
I have a big theory about this. I'll write it in long form if anyone is really interested, but the short answer is of course who you play with affects you. The people we are with affect how we feel, and our own feeling can certainly affect how we play.
Pick your competeive endeavor of choice: softball, hoops, chess, sales, political debate, even marriage and friendship sometimes, there is vibe going on in all these things, especially when someone has a piece of their self-worth tied into the 'outcome'.
You know the Eastern stories of martial artists having battles with eachother just by sizing eachother up? This is an extreme extension of this principle, that the vibe, force, or feeling coming from someone is actually a tangible thing.
But bringing it back to disc golf. It's up to each of us to evaluate when to try and overcome this tendancy to tilt when playing with certain people, and when to decide that its not worth it to constantly take on some peoples' stuff.