Dan Zymborski is a fantastic baseball writer, in my opinion. He was an early and frequent contributor to the Baseball Think Factory, and still writes for ESPN - sadly mostly behind the paywall. I make a point of reading his stuff when I can. When I first discovered baseball, Zymborski was one of the sabermetricians that I followed closely, along with the guys who ran and wrote for Baseball Prospectus. Sites like FanGraphs (you can donate by becoming a member) are the modern iteration of BTF, and have yielded another generation of interesting and informative writers who pen amazing articles for free.