McDonald's All-American Chris Walker will miss at least the first month of the season, increasing the odds he comes back to school as a sophomore.
Andrew Wiggins is as good as gone after one year at Kansas. And Big Blue Nation should not hold onto much hope that Julius Randle will be back as a sophomore in 2014-15.
The 2013 freshman class is loaded and some NBA teams are already tanking to try to get one of these prospects. But not every one can go pro.
Sure, there's a reason we'll look back at this period of college basketball as the one-and-done era. Most of the players at the top of their classes head to campus with the intention of leaving for the NBA draft after just one year.
However, since 2008, there have been only seven guys in each respective class (28 total) ranked in the top 20 by Rivals.com, who have left for the NBA after one college season. (One player, Latavious Williams, decided to go pro immediately, opting for the D-League instead of college.)
The only time more than half the top 20 freshmen went pro after one year, was in 2007 (11 players). Since the NBA changed the age limit, 62 percent of the players ranked in the top 20 by Rivals.com have made it to their sophomore year.
If you were to give each top 20 player in 2013 truth serum and asked him if they'll ever be sophomores in college, a majority would probably answer no. But chances are a majority will be back. These 10 fit the profile.
Joel Embiid, left, shares a laugh with his teammate Andrew Wiggins during the Nike Hoops Summit.
Embiid, who is from Cameroon, did not start playing basketball until he was 16. This explains why he was a late riser in recruiting rankings. It's unusual for a player with such limited experience to be considered a one-and-done prospect.
Of course, when you're a true 7-footer, with feet that Bill Self has compared to Hakeem Olajuwon's, and Rick Pitino predicts you could go No. 2 in the draft, then yeah, you sound like a guy who is not going to be in school long.
The other thing to consider, however, is that Embiid will have a tough time winning a starting spot for the Jayhawks this year. The preseason favorite to begin the season as the starting center is Memphis transfer Tarik Black.
Self has been willing to start freshmen in the past but the big men in KU's program have traditionally had to wait their turn. Cole Aldrich, Markieff Morris and Thomas Robinson all came off the bench as freshmen. And Morris and Robinson did not start until they were juniors.
Embiid could also benefit from an extra year in KU's strength program.
Noah Vonleh is a power forward who can play both inside and out.
It's beneficial for a player's draft stock to be on a really good team, and Indiana could be a year away from being really good again.
This season is a rebuilding year after losing four starters.
Noah Vonleh is part of a talented class, and similar to Cody Zeller, he could be the star on a great team in his sophomore season. Even though Zeller's sophomore year was slightly below expectations, he was still a lottery pick.
Vonleh could be on a similar path. The mock draft sites apparently agree. Both DraftExpress.com and NBADraft.net do not have Vonleh in their 2014 mocks, and both have Vonleh as a lottery pick in the 2015 draft.
Kentucky freshman Dakari Johnson would likely be the starting center for a majority of college teams.
The chances Dakari Johnson is a one-and-done big man had to go up just a sliver when Kentucky center Willie Cauley-Stein injured his hand, forcing him out of action for 10-14 days.
That gives Johnson the opportunity to prove himself as the starter. It's still probably Cauley-Stein's job to lose, but if it's not a given and you're battling one of the best centers in the 2013 class, starting the year injured is not ideal.
It's still a good bet that Johnson will return for his sophomore season after Cauley-Stein goes pro. On the 2014-15 Wildcats, Johnson could become one of the go-to guys and have way more opportunities to prove himself worthy of a first-round draft pick.
Rondae Hollis-Jefferson will likely come off the bench for a deep Arizona team.
Rondae Hollis-Jefferson has to be rooting for Aaron Gordon to play the 4, which is probably his more natural spot.
Either way, Hollis-Jefferson fits in more as a role guy in Tucson than a star. He might be a McDonald's All-American, but he's a year or two away from becoming a go-to guy for the 'Cats, and likewise, he could be a few years away from being ready to go pro.
Marcus Lee is the lowest-ranked McDonald's All-American in Kentucky's loaded class.
Marcus Lee has the most difficult route to playing time of any of the Kentucky freshmen. He's behind Julius Randle, the top-rated player in this class not named Andrew Wiggins.
Randle is going to play a lot of minutes, and in most years, Lee could simply slide over to the center spot and get minutes there. The one issue here is that Kentucky has Willie Cauley-Stein and Dakari Johnson.
This will be a good year for Lee, who is only 215 pounds, to add weight to his slender frame and learn Kentucky's system as he waits his turn.
Chris Walker is not enrolled in school yet. And the plan, according to a CBSSports.com report from Gary Parrish, is for Walker to enroll in the second semester, and be eligible in mid-December.
Let's assume that happens... Walker will still have a hard time working his way into the starting lineup. One post spot is locked down by Patric Young—the other will be a battle among Dorian Finney-Smith, Casey Prather, Will Yeguete and Damontre Harris.
Finney-Smith gives the Gators a three-point threat, and both Yeguete and Prather are good weapons in Billy Donovan's full-court press. So if Walker ends up coming off the bench, will he be able to do enough to prove he's a first-round pick?
The better option for Walker could be to come back as a sophomore. He can be the replacement for Young and has the potential to be a lottery pick in 2015.
Kasey Hill will be surrounded by veterans in Gainesville this year.
Florida head coach Billy Donovan has a history of convincing guys to stick around for an extra year.
Remember 2006? The Gators had three guys who may have been lottery picks on that team. They all came back to school to win another title.
Even the one guy who has left the program after his freshman year, Bradley Beal, sounded like he felt the pull to return.
Point guard Kasey Hill will play on a veteran team this season, and the temptation for a guy in his position is to do everything possible to make the older guys look good.
Hill could return as a sophomore and it would be his team. And a possible duo of Hill and Chris Walker as sophomores could be fun.
Memphis has four senior guards who could all end up starting. They will be the stars. They will be the scorers. And that's a nice luxury for incoming freshman Austin Nichols, who would be the leading candidate to be the fifth starter with those four guards if Josh Pastner decides to go small.
Regardless of if all four guards start or not, Nichols, the top-rated player in Pastner's deep class, will not feel the pressure someone in his position would typically feel. Nichols can be a complementary piece.
As for his one-and-done prospects, it's probably going to be hard to get enough shots to put up the kind of numbers that would get noticed.
As an undersized 6'8" power forward, it may not have mattered anyway.
James Young is the third Wildcat to make this list. The assumption here is that all six freshmen can't go pro, right?
If they win a national championship, don't rule it out. But what could bring a guy like Young back is opportunity. As in, the opportunity to be a star.
Right now, John Calipari doesn't have his usual star-studded freshman class lined up for next year. That could change, but it's not as promising as years past.
Young will battle Alex Poythress for the starting spot at small forward, and it's likely the winner leaves after this season. But if one of the freshmen who has to come off the bench ends up leaving, it would probably be Young.
The minutes will be there for Young, as he can be the backup at both small forward and shooting guard. My point being, Young's opportunities might not be as limited as Dakari Johnson and Marcus Lee.
Jabari Parker would be the biggest surprise to return for his sophomore year out of this group. At a point in time, Parker was the top-ranked player in the 2013 class and he's considered a top-five pick in most mock drafts.
But Duke is one blue blood that has been able to keep its players around for more than a year. Think about all the talent Mike Krzyzewski has had roll through Durham. Now, do you know how many one-and-done players he's had?
Four. Corey Maggette, Luol Deng, Kyrie Irving and Austin Rivers.
The other part of this is the potential to play on a national championship team in 2014-15. Duke is considered the leader to land top-ranked big man Jahlil Okafor and point guard Tyus Jones.
If you pair those two with Parker, there's no chance any team in America will be able to match the talent of that threesome.
Duke would be a unanimous preseason favorite. And if Okafor ends up at in Durham, the Blue Devils' depth in the post will improve, giving Parker the opportunity to prove himself at the 3. He's expected to play mostly at the 4 this year.