I want to say several years prior to the creation of ECNL, Chelsea was a formidable club with several formidable teams (wasn't it home to many top girls from the class of 17 that will be playing in college?). IMO, all of the clubs in the North OC are ok for younger ages but once the kids start approaching Jr. High, many will go to top programs (ECNL and now Academys) so as to continue their personal growth with the game and pursue dreams of playing in college.
Just because a club has a big club's name attached doesn't really mean anything other than trying to dupe people into thinking that they are someone special because the girls have to pay top dollar for uniforms that say Slammers, Surf, Pats or Legends. If your kid wants to play in college, the odds are better if they play on the A teams from Slammers, Surf or Legends (Pats if you have a boy). Playing for any satellite club really doesn't do much to increase one's odds of making the A team in Chino, Mission Viejo, Newport or SD--being better than the current starters does.
Now, if you have a kid that is going to attend a specific high school and they don't play for a top team, and they are realistic about goals for soccer, it might make sense for them to play, for example, Legends OC if they are going to attend Esperanza HS, because the DOC for Legends OC is also the coach at EHS. I wouldn't say that it would be too far fetched that the other coaches from Legends OC might have some type of connection to EHS. The same could be true of other schools too.
If I were Chelsea, I would do whatever possible to make a connection with YLHS otherwise I don't see Chelsea being much more than a glorified version of JUSA signature.