Just as an example of how I said the MLB.com transactions glossary is clearly not intended to be a detailed rulebook, take this passage from the Options entry: "If a player misses an entire option year due to injury or expends his third option year before he has completed five professional seasons (Major Leagues and Minor Leagues included), he can receive a fourth option year." By that definition, Kennys Vargas should not have been eligible for a 4th option year last year, as he had not missed any seasons to injury and already had at least 7 professional seasons (2010-2016). But we know that he was eligible for the 4th option. And if you read the details in the actual rule book as linked by ashburyjohn, or at the Cub Reporter site I linked, you will see that the actual definition of "complete" or "full" professional season means at least 90 days active (with some qualifiers about which disabled list stints count, and which do not) -- thus most rookie league seasons don't count toward that number. So Vargas WAS eligible. The MLB transactions glossary wasn't wrong, it was just a general overview without the details. Similarly, the Rule 5 entry you quoted is basically true -- you can trade for a Rule 5 player and assign him to the minor leagues -- but it omits a few details for the sake of brevity, like the fact that he has to clear waivers first. Broadcasters and reporters often omit these details too, about complex but relatively minor transactions. (And Rule 5 might be one of the most complex, yet most minor, rules in MLB ) Sorry to seem like a stickler! I respect any and all opinions on this board, but I try to provide the most accurate transaction rules where I can.