Does a dynamic site rank lower in Yahoo!?

Would the changing keyword density cause a lower rank

[andrewshim]

After the April 21st update, my site's been bouncing in and out of the top ten, but looks like I may have to accept that I'm going to be at #22.

Checking the sites above me for keyword density, backlinks, (even) anchor text, meta tags, there doesn't seem to be any pattern that I can emulate. What I did find was :

- most of the sites above me are older (can't help this)
- 99 percent of the sites above me are not dynamic.

Question is... because my site is dynamic, the keyword density changes with every update. Would this in any way affect my ranking? anyone have similar experiences?