"The point of clarity is for the OP. He's Junior in HS trying to process this information. His application will be treated just like every other student who applies test optional no matter what his economic, first language or athlete vs non athlete status might be."
Yes, absolutely unless coach supported, his application will be treated as every other applicant (i.e. into the black box of an admissions committee).
I have no knowledge of that process; but I do note that UC admissions standards haven't dropped AND the pool has grown much larger. This implies that an already very low acceptance rate has dropped even further.
If a kid isn't coach supported, his baseball is viewed as an EC and will be measured against other ECs. Schools like UC want more than "just an EC;" these schools want to see ECs wherein the applicant was in leadership, passionate about the EC (e.g., nationally recognized [model UN, Seimens or ISEF, published author, etc.]), and stands above other (tens of thousands) of applicants. These schools want to see perseverance and a kid who "beats the odds;" that could mean a homeless kid heading toward valedictorian, a rural kid inventing a method to heat chicken coops, really anything which separates applicants. (And, if the coach isn't supporting you, you haven't separated in baseball, leaving other ECs to carry the load.) These schools want quality, not quantity type ECs.
As for cutting the FA corner, UC is need blind.
OP re: financial aid. Most peer schools to UC have very similar FA - meaning middle class (and lower) families receive steeply discounted to free tuition maybe even extending that aid to room and board.
PS. (From Gunner article: "Students who chose not to submit were admitted at lower rates than submitters. . ." So there is no advantage to a high scorer leaving that box blank.)