I never figured what someone else did with their kids was my responsibility to judge. In public schools kids can't play if they turn twenty. In privates anything goes. I was amused freshman year my son was a 5'6" point guard dishing off to 6'4" bigs. Some of them were twenty months older.
Both of my kids were seventeen on graduation day. With my daughter it didn't matter. Girls physically and mentally mature sooner. With my son, since he was asked to play 17u when he was 15u eligible by a couple of weeks there wasn't an issue. He had played 16u the year before. He was a stick when he was a freshman (5'11" 135) and a lot stronger than he looked soph year at 6' 160. He was asked to play 17u after the summer he was 5'11" 135. Even travel ball coaches project. Had my son benefitted physically with recruiting by doing a PG year it would have been considered.
I started school at four. As a preteen I starred age based youth sports. When i got to middle school I was a year to a year and a half younger. I was middle of the pack in sports of those making the teams and socially immature. In 8th grade I started dealing with depression due to the challenges being younger was causing. I was purposely not doing well in school so i wouldn't be the younger, smart nerd anymore.
We moved. My father decided to have me repeat 8th grade to place me my age group. No one would know. My mother was pissed. My father got it. He was a three sport star and played college football and baseball. The change moved me from the middle of the pack size wise and athletically to making varsity in three sports soph year. My mother was happy my grades went back up (until there were other issues).