I think I've posted about this in the past, but it bears repeating. If it is AT ALL possible, split your drums out to separate outputs. Now, you can feed your bass player some extra drums (in his monitor), to get him back in the groove.

Most musicians have troubles locking to arrangers because they aren't used to hearing the drums buried in the mix. They stand next to him, and can't miss it! And many of us make the problem even worse, by burying the drums by what WE play! Listen to most demos here... The drums are usually close to inaudible compared to the lead sounds. Now imagine your job was to lock to the drummer. Tough!

The answer is to record yourselves during rehearsal. Then listen critically, and try to decide when the drums are swamped, and adjust the Performances or SMF's etc., to make sure they don't. And one of the things that is going to have to happen is for YOU to get used to hearing yourself more IN the mix than ON it.

If you can split out the drums, you are pretty good to go. But if you can't, it is going to take a bit of time for BOTH of you to adjust. But don't give up. Record EVERYTHING (those little Zoom pocket recorders are killer for this), and try to listen objectively. Don't worry about YOUR part, or his part, try to listen to it as if it is a BAND... Do they sound balanced?

If they do, your job is done!