| Sergio,
I think the reason rhythmic accuracy seems harder to acheive on a gig as opposed to a metronome situation is that there is a human element to it. You're dealing with emotion, interaction, and multiple creative personalitites. You have to spend time working with as many different drummers as you can and figuring out what the common thread to a drummers playing is. There are many things I look for from a drummer such as being responsible for their time, listening to what's going on around them, their dynamic range and ability to use it, and melodic content in their playing.
You will find that in many situations a lot of these aspects of the music are missing and should beat yourself up about a groove not feeling so great. But you have to be able to tell when it's you who is lacking any one of those things as well. You can't just automatically blame the drummer if a groove isn't happening.
The only way to practice that is to get into as many live or jamming sessions as you can. Time will help you build up a note book of things you like about other musicians, things you know you need to work on yourself in order to fit into a situation, certain types of playing situations to avoid, and playing situations to seek out.
You also have to be responsible for your own time in a big way. You can't rely on someone else in the band to be able to lean on throughout a performance. That is true for anyone in the group. And unfortunately it's not true all the time when you're in a performance situation. You feel certain people relying on the drummer to show them the time, or piano player to show them where the harmony is.
When you're practicing you should be concious of where the changes are, where the groove is, and be able to recall the melody of a song at anytime if you feel yourself getting lost.
Practicing at home is cool, working with loops to shed your groove and pocket. But there's nothing like actually being in a band or on a gig all the time to get that stuff together.
Easy,
Janek | 
