Complex sentence: Players attempting to play in MLB often choose not to defect to the United States, because establishing residency in the United States means they must enter the MLB Draft rather than being free agents, allowing them to choose their offer.
Split into simpler sentences: Players attempting to play in MLB often choose not to defect to the United States, because establishing residency in the United States means they must enter the MLB Draft. If they defect to another nation, they can become free agents, allowing them to choose their offer.