in the pocket

The phrase In The Pocket is used to describe something or someone playing in such a way that the groove is very solid and with a great feel. When a drummer keeps a good metronomic pulse, often referred to as keeping time, and makes the groove feel really good, and maintains this feel for an extended period time, never wavering, this is often referred to as a deep pocket. --------------------------------------------------------------------------------

It's impossible to have a pocket without also having a groove. 

For those that understand Logic statements, it would look something like this .....

Let p = pocket
Let q = groove
Given: good metronomic pulse

The Statement:
"if no pocket then no groove."
That is:
"no pocket implies no groove"
Or, symbolically:
¬p --> ¬q.

By definition of the principle of contraposition or negative inference, then:
p --> q.
That is:
"pocket implies groove".

Therefore, if you have, in fact, achieved a pocket, you must have had a groove in order to have created it in.

Notice that mathematical logic does NOT imply that if you had a groove you have in fact achieved a pocket. That statement would be false and would look like this: p <--q = F