Have you actually seen mealybugs on them? This may be off the mark, but the picture looks similar to the damage from black vine weevil. Google "yew black vine weevil damage" and you can see several examples of the notched foliage and stems (mostly interior foliage). If you find similar, it would do no good to plant more yews until it is eliminated from the soil where the larvae develops, destroying roots and creating an appearance similar to your picture.
hortster

I haven't seen anything that looked like a weevil. I did see these white fuzzy things that looked like mealybugs. I wish I could figure out how to upload another picture that I took of it.

Maybe those lower branches are not getting enough sun?

Have you posted a picture of the 'white fuzzy things'? I'll bet a dollar that it's one of the cottony scale insects, and NOT mealybugs. Cottony scale is pretty common on Taxus in the northeast. Mealybugs? NOT!

Kimmsr has a point about the sun. The shape of your 'yew sculpture' is the exact opposite of what would be required to allow plenty of sunlight to all portions of that plant. Hedged plants should actually be a little bit narrower at the TOP than the bottom.