Cold shade in Winter, even a nearly-frost free California Winter, could be contributing to the worn state of the leaves.
However, changes to soil and watering conditions might also help matters.
First begin to water somewhat more deeply, but significantly less often. The exact frequency is determined by observing plant response, but I would start with watering once a week in Summer, and significantly less than that in the cool season.
Secondly do what you can to improve the soil. At the very least, apply a thick, 2 to 3 inch lair of organic woody mulch to the surface. Wood chips or redwood bark would be ideal. Also consider adding a living ground-cover. Additional low plants would not compete against your Dracaena reflexa var. angustifolia, but would rather encourage a more insulated and well-draining topsoil layer. Consider a shade-tolerant ground-cover such as Lesser Periwinkle (Vinca minor), Begonia, Impatiens, etc..
A more laborious improvement would be to lift the plants, amend the bed, and then replant them on low, gentle mounds.
Also, as the weather begins to warm in Spring give the bed a feeding with a complete liquid fertilizer. You will want to encourage a flush of new growth torepalce all the tattered leaves from before.
