Jack never had a groove concept in a classic sense, his playing could be angular and he took liberties with time and meter (and on fretless: with notes!
) like, say, Carlos Santana does in his lead guitar playing. That is just him. The good JAE was no groove monster either (there, I said it), neither was Chris Squire. Robbie Shakespeare or Bernard Edwards they weren't!
Macca grooves! Without ever giving a thought to it I believe. And even though his rhythmic approach is pretty much meat and potatoes, but he swings in everything he does.