Dymero - 6:05 pm on Feb 18, 2013 (gmt 0)

I'd base my decision on a per-page basis (or per-type of page basis if you can categorize poor pages):

-If you think you can re-write a poor page sufficiently, do it. If not, consider deleting and redirecting.
--Caveat: If deleting page is going to result in a long period without posts on your blog, you might consider just gritting your teeth and trying your best to improve at least some of the posts. That way it won't seem as if you were inactive for a period of time.
-For those pages you think may be seasonal, check your Analytics on the pages, and that should provide insight. If you don't have any stats on the page there, go to Google Trends and see if common keywords from the post have a higher rate of queries at a certain time of year.

As for page with out-of-date information, I think there may be some value in writing an entirely new post on the topic and redirecting or leading people to the new post in another way. In some industries (particularly SEO), this could represent an evolution of knowledge over time. You got it right once-upon-a-time, but now something has changed.

I probably would not delete a page or post due to link value reasons, especially if it's moderately valuable. You may not be seeing a return on inbound links now, but you may in the future.

I'd also be careful about considering a page "poor" just because it doesn't have backlinks. Not every post can be non-fiction Shakespeare, as it were, and not every post will get backlinks. I think people expect that some posts will be lower quality than others, especially on a blog.

But for the absolute worst posts, I'd definitely do something about them. Then move up from there.