Hi fmaziers
I’m replying to a quite old post, I know, but I relate to what you’re describing (you’re shape getting disorganised when you start doing staccato). I just found out that I also got to the point where I had a good shape after the aa — ooh, but when the staccato starts, my corners seem to relax with every note I play (going back to the relaxed aaa-feel). So I focused on that this morning, keeping the exact same shape/tension during the 16th notes (very slowly though) and I got a whole new feeling about how a staccato could feel and sound like.
Maybe this could help (as far as you didn’t resolve it already).
Very curious myself what this will lead to!
Good luck,
Tom