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