As Stephen said, most of the staff does something similar to that. I always say that it's preferable to be on the team rather than not, because then you'll know what everyone else is writing, and what kinds of articles might be needed. It's not as if super-sensitive stuff is discussed in the Tar...
As a note: If you don't have writing samples, that's fine. Just make sure that your application proves that you can write well-ish, and that's good enough. Doesn't have to be super-long, either! I'm pretty much willing to accept anyone, since I'm willing to take the time to edit and stuff. <3...