On paper this sounds really great-- but the logistics make this unworkable. Here's what you have to keep in mind:
1) Coaches have to schedule conflicts based on driving time, etc., well in advance, so they can trade spots within their club. ("Cover me on weekend A, and I'll cover you on weekend B"). Moving teams up or down within a season makes this impossible.
2) Parents have to schedule the same for families where more than one kid plays. Again, unless all teams play at the same complexes constantly, you can't ask parents to be able to juggle this, it's just impossible.
3) There are too many teams out there to have all the teams play at the same complexes constantly.
4) It is impossible to stop unscrupulous coaches from sandbagging their "placement" games, and they don't even have to have the kids in on the scam. All it takes is for them to sit their best goalscorer or instruct the kids to use these games to learn how to play out of the back, and then the natural mistakes lead to losses.
5) It is impossible to stop unscrupulous clubs from using club pass players to win specific games.
I think it's important to recognize that any kind of team placement situation (I hesitate to call it pro/rel because it shouldn't be tied to record) can and will be gamed by parents and coaches who want to win. You can't go around implementing any kind of game monitoring system because that requires a level of coordination that neither Cal South, nor the leagues, have any incentive to invest in.
The reality is this-- you have four buckets of teams out there:
Beginners, who are just above rec level, just starting out and learning the game. It is in everyone's vested interest to have these teams play each other and only each other. It's fine for one of these teams who has a super athletic kid play up front and score a ton of goals who winds up being their bracket's mvp, you're always going to have that one kid playing above their league. What you want to avoid is having one of these teams wind up playing against established teams and get blown out all the time-- that winds up getting teams to disband. Classify these teams as having 0-1 years of experience tops or eligible teams from the bracket above who won less than 25% of their games.
Competitive teams who have a hard time winning. These are the teams who will challenge any other team but for whatever reason have a hard time scoring goals, or still make more mistakes on defense than they can make up for on offense, you know the drill. Classify these teams as 2-4 years of experience or coaches self-select teams from the bracket above who won less than 25% of their games, or coaches self-select teams from the bracket below who won more than 50% of their games.
Competitive teams who can close out a game. These are teams from the below bracket who have more scoring threats. They will consistently beat other competitive teams but who have a hard time eg winning a tournament when they go up against upper tier teams. Classify these teams as 3-5 years of experience, or coaches self-select teams from the bracket above who won less than 25% of their games, or coaches self-select teams from the bracket below who won more than 50% of their games.
Upper tier teams. These are the teams ready to take the step to what used to be the DA, or ECNL, etc etc. They will consistently win tournaments. Classify these teams as 3+ years of experience with coaches only self-selecting these teams but who have to have won 50% of their games from last year.
I think this is a good balance-- coaches aren't forced to win every single game, there is clear progression here, and there isn't automatic pro/rel for kids. Every game needs to be competitive but we recognize that there will be a percentage of games that simply won't be competitive. This kind of bracketing doesn't require any additional infrastructure to implement, lets the unscrupulous coaches stay within their lower brackets if they just want to win their Europa League, and the number of blowout matches is kept to a minimum.