The only time I ever used the disc was in the first game I played (or if I'm just messing around). When I first started, I got a decent amount of kills with the disc by shooting peoplel who were shooting at my teammates - upclose it isn't nearly as effective.
Right now, nobody with any sense uses the discs. Is that what you intended? I see very few Frieza's, and the Cells I see never use the disc. Its not easy to hit a moving target with the discs - especially since they don't have an area blast like most things.