In my experience at least, having good content on the page is not necessary. Neither is having the keywords I'm trying to rank for, on the page I'm trying to get ranked.
For ex: I got a clients' homepage ranked at #1 in Google for 2 diff. keywords.
The keywords are in the Title tag, Description tag & Keyword tag but NOT anywhere on the homepage. I use those 2 keyword terms in the anchor links back to her site. The homepage has been #1 in Google for about 6 months now.
ALL the backlinks come from high PR blog comments, edu, gov & com forum profiles and authority sites. NONE of the backlink sites are relevant to her niche. There is no relevant content in my blog comments either. The comments are related to the blog posts only.
I'm not seeing the necessity of relevancy, yet.
Edit: I forgot to write that she has a blog in a subdirectory, like
www.domainname.com/blog
I'm sure the blog, which she updates daily, has a LOT to do with her rankings b/c I haven't built any backlinks for her in like 5 months.