Interesting read: http://www.cbssports.com/collegebasketball/eye-on-college-basketball/24702787/a-rare-recruiting-restriction-is-hindering-sec-basketball-growth
To summarize: "...the SEC does not allow its member institutions to sign and enroll prospects who do not spend at least three semesters at the junior college from which they graduated." So a player like Crowder, cited as the example, wouldn't be able to compete at an SEC school.