I typed out my entire review and it got deleted. Frustrating, so I'll summarize as best I can.
I had a major issue at the beginning figuring out how all the story lines were going to meld together. I didn't think they were going to, but they came together rather cohesively in the end. There was one section where I figured out what was going to happen before it did, and I wasn't at all surprised when it was revealed. That's okay. I think the author meant for that to happen.
I have a difficult time believing this is a debut novel. There are authors who've been writing for years who fail to capture my attention the way this book did. Kudos to Mr. Harbach on that.
I loved the characters' back stories, and I loved how easy it was to read through the baseball and not be bored.
I'm not doing this book nearly the justice I just did, but I can't remember half of what I said because I spent nearly all day writing the review that got erased. Suffice to say this is a must for all baseball fans.