Playing REALLY tight is a skill that has to be practised and studied like music theory, etc. What do you think why Bass Players studying at BIT or any other bass university play simple 8th and 16th note grooves for months although they can already play the fastest runs and craziest slap parts? Playing a bass line correct and laying down a groove like only some masters are able to is a BIG difference.
I don't know how far you are in your own muscial developement, but I tell you the better you get the more you will be able to appreciate tight rythm playing. After my study of guitar at MGI(german version of GIT) I hear VERY slight variations and imperfections in rythm playing I would never have been able to hear before. And exactly these fine nuances seperate a master grade bass player from a good bass player. For example I had a band class where I played with Al Di Meola's drummer and the head teacher of the bass school who also played for Paul Gilbert and if you heard them play a simple eight note beat it just sounded incredible and way more gripping and grooving then what your average good bass player can deliver. There is a big difference between playing "correct" and playing like one of the bass greats.
Anyway I would NOT put Anthony in that calss of players, but he still is very good in terms of rythm.