Soil issues may be adding to the problem (soil amendments can definitely cause problems), but these plants are what one frequent poster would call foo-foo plants. Sickly ones are much more common than healthy ones. I would take this as nature doing me a favor by getting rid of these awful things, and choose a more reliable type of shrub or plant.

thank you brandon7. What short to medium sized shrubs would come to your mind as being reliable on a hillside? Would you mind sharing the thoughts?

I can't suggest specific plants as my growing conditions are too different from yours, but have a couple of general thoughts that may help your replacement plants grow successfully.
- Don't just amend the planting holes; add amendments to the whole bed or don't amend at all. Particularly in clay, amending only the planting holes creates a pot effect where water is trapped in the holes, and roots don't grow out of the holes due to the abrupt change in the soil texture.
- It looks in your photo like you may have used landscaping fabric. (If you didn't you can ignore this.) You'd do much better with a good layer of organic mulch such as pine straw or wood chips, replenished as needed. It will slowly break down over time and improve your soil. Any bed will need some weeding, but weeds will be easier to pull in a well-mulched bed without landscaping fabric. The landscape fabric will get weeds rooting into the fabric from on top, and it will reduce the health of the plants' roots below. If you really want something under the mulch, corugated cardboard or multiple layers of newspapers will do a good job of blocking light and reducing weeds while the mulch and plantings settle in.
- Look around your area for healthy plantings in similar sites, on a hill and with similar light levels that appeal to you. Take photos or ask homeowners (many gardeners are more than happy to talk about their gardens) to get plant IDs. You can take photos to a nursery or post them on the Name that Plant forum here on GW. That way you will be starting with plants that like the conditions you have.
- Go to one or more good quality full-scale nurseries with photos of the site, both from the side to show the angle of slope and from head on. Their staff should know what grows well in your area's soil and weather conditions.

nhbabs, what great thoughts you have for me! Thanks bunch

You don't have DEER do you?! I used to love growing these--but the deer love eating them more. Probably one of the top 10 of shrubs on their menu favorites. Disagree with them being foo foo though. Locally, they seem quite healthy and robust--as long as your neighbors do not include deer.

Yes, often when the top goes bad it is because there is a problem at the root. On another note you are getting quite a bit of reversion on the earlier planting, one near the front (as seen in the picture) has become quite green. The way to fight this is to snip out green shoots early in the game and keep them snipped out.

Thanks for all the replies. To njoasis, yes I have seen deer quite often. However, I did not see them as often as before when I planted these shrubs on the hill.

I can't tell from the photos, but these are susceptible to scale which will kill off the leaves like that. Also, it looks like a fair amount of some type of conifer needle on the ground. Not sure if this is the cause but I have 8 silver king euonymous across the front of my house. 4 of them do great, the other 4 which happen to sit under the neighbors spruce tree and get a fair amount of needles on the ground, are much more sparse and do not grow nearly as quickly as the other 4 which don't get any needles.

Might just be coincidence in my beds, this is the only difference, same water, same sun, same soil, just that one side gets a coating of needles and the other does not.