Let's cite another example. Ahn & Gibbs played at Carson WTA 2009. Sabs did not. (Nelson did play and defeated Baltacha)
I get your point. Honestly, it is a bit redundant.
My point is this...
There are other factors why a player develops at the college level more so than at the junior level (aside from going to USC, which seems to be your point).
Ellen Tsay touched upon this subject matter saying that certain players thrive at the collegiate level.
Perhaps college provides a level playing field for some players to get more exposure and opportunities to play the big tournaments or play seeded players and teams.
At the junior level, economics may place a ceiling on such opportunities.
Sabs got to travel a lot this summer at those World University games.
I am sure those opportunities weren’t available when she was in high school.
Despoina Vogasari chose to go to U of H and that has allowed her to play the Pro Circuit here in the US, as oppose to the limited matches she can play in Greece.
2. Player Development
Most of player development opportunities are because of having a support group in a team environment and coaching staff. Not all junior players can afford coaches and some rely on parent coaches or friends of family so this is somewhat an extension of economics.
Having a system in play to track a players schedule, work-outs, matches, and tournament play results in more opportunities.
Without this system, a player may forget to register to get a W/C entry at the US Open.
3. Academic Challenges
Playing for the school might allow professors to give the players some consideration but that doesn't change the academic requirements.
Some of the elite junior players have been taking online courses or been home school, so its an adjustment to attend classes and still put those hours on the court, especially with a lot of studying to do. Some colleges have more academic challenges than others. Ahn skipped Indoors because of her classes. Meanwhile, a bus-load of players from USC and UCLA are in New York.
4. Turning Pro vs. College Degree
If a player, plans to do her best to advance to the pro level then that has a lot to do with their development. If their goal is to get a Stanford degree and get a good job (like Stacey Tan) then at some point they will lose to other players, who try to advance their games at the Pro Circuit (like Brianna Morgan). Someone mentioned that most of the Cal players, their end goal was to get the tennis scholarship.
5. Different Mindset: Team vs. Individual
At the junior level, it’s a different mind-set than at the collegiate level, where team is first. Lauren Embree touched upon this subject that she has to refocus back to when she was playing juniors in order to succeed at the pro level. Some players thrive at the team is first concept and play better at duals and team tournaments than at individual tournaments (like Embre and Barte).
I am just saying there are a lot of factors that contribute to how a player develops in college, which is independent upon their success at the junior level.