Shadorne, it’s possible we may be saying the same thing depending on our definition of our choice of terminology, but I have to disagree with your definition of "in the pocket". I have never heard a musician use the terms "in the pocket" "in a deep pocket" or "player x has a lot of pocket" to mean that the time "moves". Quite the contrary, it refers to a very very steady sense of rhythm with a "good feel" attitude; what some call great groove, funkiness etc. (what I referred to when I said that Stubblefield’s playing was relaxed).
I am sure you have heard a metronome produce "perfect time"; a sequence of absolutely perfectly spaced clicks. But perfect time does not mean "feel good" or "swinging" or "funky"; a metronome is after all just a machine. Think of each one of those metronomic clicks in time as a dartboard with a series of rings and a bullseye in the center. Each of those perfect clicks occupies a certain amount of space in time and there is a certain amount of acceptable latitude (rings) on either side of the rhythmic bullseye as would be defined by the very center of that click, but only as long as the player’s pulse dart stays on the "dartboard". As in darts, hitting any one of those rings can be considered hitting the target; but the closer the pulse gets to the bullseye, the more "in the pocket" it is. One of the two main things that define a player’s (not only drummers) sense of rhythm and unique time feel is wether his personal concept defines the pulse as being on the front side or the backside of the rhytmic bullseye. This is why some players have a very relaxed feel (back side) and others have a very "up" feel (front side). The other aspect of a player’s concept that defines the rhythmic feel is how the pulse is approached or set up by the figures he plays. Stubblefield was one of those players whose pulse was always, not only in the bullseye, but dead center in that bullseye and perhaps just a smidgen on the back side of the pulse (relaxed). The key was that it didn’t waver ("move"?); it was steady as a rock. Sure, the drummer can manipulate or play with the time but the PULSE generated has to be very steady to be "in the pocket".
Regards.