there are thousands of pieces that I miss
All performances are complex, and when coaching, it is impossible to attend to every minute detail. Formative assessment - active coaching - is individualized feedback to improve overall performance. Evaluating that performance, is to focus on the performance as a whole.
“performance'' because I teach physical education
I think a performance focus in important in a lot of fields because, ultimately, education is about what folks are able to do. Knowledge of things is not useful until it is applied to some problem or task. A performance focus could improve assessment across the board and shift teachers away from merely testing "content".
address both the process of learning as well as the performance or outcome
Assessment of process is commonly formative; while assessment of performance outcome is often summative, though formative assessments do look at performance outcomes too - from the perspective of informing improvement.
what useful things I could say about assessment that wouldn’t expose me as a fraud
Imposter syndrom is common as people move into more specialized fields. It's common to hear about it from PhD candidates and from PhDs.
De-emphasizing grades
going gradeless