Why YJ B will not ever amount to much:
1) Your best players will move to A
2) You will get A's bottom players, some who are disgruntled, the others not as good as the players who moved up.
3) Players/parents who think should be on A will leave.
4) Your roster will be filled in with new players to make the numbers work. The new players then have to acclimate, regardless of talent. By the time they do, the season will be over and you go back to step #1.
As I said, enjoy the ride. Be happy your kid is playing and hopefully getting better. How your team is ranked means nothing.