Do I Lose All Rights When I Blog?

Dear Rich, I was recently accepted as a writer for a major national syndicate of blogs covering sports teams. This company does not have a physically-signed document per article as is traditional with journals, to clearly state a work/submission is considered "work-for-hire", (where full copyright is given to the publisher from author). Instead, there is a blanket document called, "Content Standards for Contributors" that all writers must click-sign prior to writing for one of the blogs. In this is the following line: "You hereby irrevocably grant to us the right, but not the obligation, to reproduce, modify, adapt, publish, broadcast, license, perform, post, sell, translate, incorporate, create derivative works from, distribute and otherwise use the submission in any and all media, now known or hereafter devised, throughout the universe, in perpetuity, without according you any compensation[...] All submissions made by you shall be the sole property of ***** and will not be acknowledged or returned. " My question: Almost all writers, including myself, for these blogs are not paid, are not contracted, nor are they employees, but according to their "content standards" the act of publishing on their site results in the transfer of the copyright of the article. Is this "agreement" legally binding, and considered ethical?  
A click-to-agree contract is legally binding in the U.S. and the fact that you don't receive any payment does not prevent it from being enforceable (as long as the arrangement provides some benefit to you-- for example, increased exposure versus obscurity).
Who owns what? We think a blogger entering into this agreement retains copyright. We don't think the statement, "All submissions made by you shall be the sole property of [company] and will not be acknowledged or returned," transfers copyright ownership (It seems more like a vestige from publishing agreements relieving the company from having to keep track of email or paper submissions.) We believe a court would require more explicit language affecting a transfer -- for example, using words such as "assign," or "transfer," and "copyright" and "ownership."
What type of copyright? What you retain, after entering into this agreement, is a partially-gutted copyright. That's because you give up a lot of rights on a nonexclusive basis, effectively preventing you from selling those rights to someone else on an exclusive basis -- for example,  entering into publishing agreement for a collection of blog entries as a book. But, of course, that may be "old school" thinking, ignoring the benefits of your personal brand exposure and the temporal quality of sports blogging.