Something that really got me thinking after seeing Keith Jarrett's trio play was observing KJ's touch. Now I have the records so I've heard it before. But when listening to it on a record, I turn up the volume and the piano is mic'ed. In a live performance, where you can really judge the true volume of the piano, I was suprised to hear how gentle his touch is on EVERY note. Every note is rounded tonally. This would mean such control over the dynamics at all times.
Incredible to me when playing jazz since while improvising, you often don't know where you'll be going next until the moment. So there's always akwardness in hand and finger position and resulting in unevenness common to most jazz pianists. But not with KJ.
Since this is obviously a lifetime of training to develop, (and I'm past having that kind of time), at least being conscious about it is better than nothing.
The other thing that I learned was to distinguish "harmonic embellishment" in KJ''s playing and the "melodic phrases". I didn't observe till now that there's a tension and release between these two approaches and that this gives one, your "voice". Lots of practice involved here to balance these two with deliberate control. There's a difference in phrasing between the two as well. I find that the melody making side is like a singer and there's a lot of rubato phrasing. Such a contrast to just bebop blowing.
This KJ concert was like a major jazz lesson.