I'd approach this interesting situation from a different angle. Instead of focusing on panning and artificial ambience, I'd first concentrate strictly on the quality of the sound.
If the three mics were actually positioned in a straight line coming out from the middle of the four players, I think it's fairly safe to make some observations on that basis:
1. Unless two of the mics were configured as a Mid-Side (MS) pair, or some other unknown factor is at work, there will probably be little or no stereo information available, so you should probably consider this to be a monaural recording.
2. If the mics were really positioned at three different distances, then the farther ones will be delayed with respect to the nearest in this fashion: the amount of delay will be slightly less than 1ms (1 millisecond=1 thousandth of a second) per foot of distance since the speed of sound at room temperature is roughly 1,100 feet per second. For example, if the distances from the near mic were, say, 8 and 16 feet, then the other two would be delayed by roughly 8 and 16 milliseconds, respectively.
3. Unless the distances were much less than the example, I'd guess that the summed phase error when you mix the three in mono would yield a pretty indistinct, blurry sound.
4. Even though you don't know the distances, you should be able to "tune out" the delays by experimenting with different amounts of delay on the middle and far sources. You should be able to do this by comparing the close one to the other two one at a time, with the two that you're currently comparing either summed to monaural or panned to extemes, or even try it both ways to see which resolves the phase relationship better. If my hunch is right, you should be able to easily notice an imrovement in the phase corrected sound, at least if the distances were great enough during the recording session.
I'd start messing with other techniques only after a successful job of time alignment. I suppose that then the sound might benefit from the things you've been trying. This is just a thought experiment at this stage; it would be interesting to find out the results of any experimentation you might actually do. It's good food for thought, anyway!
