Brilliantly put Yeah, but knowing the source of the traffic is essential as you understand in which area you need to do more SEO
Off late observation .. One of my site lost some rankings on Google, but picked up great on Yahoo .. Wonder whats happening :? /G
The important thing is How many visitors is that position on Yahoo sending you? Anyway, what usually happens with me is, if my sites start to rank in Yahoo or MSN, I start ranking in Google pretty soon and the traffic from yahoo msn goes down to 3-4% of total.. Of course, it helps that I tweak the site once I see the yahoo ranking