Playing up has advantages and disadvantages.
My daughter's 4th grade team has dominated every 4th grade team that they have played. They often play against older teams to find the competition that they need to get better.
I understand the concept but it can be humbling and risky. How? Why? The younger girls could lose their confidence, create bad habits or get hurt.
The Main Point
I worry about the injury risk because my daughter is so small compared to many of her teammates and the older competitors. I am not worried about her confidence because it soars when her team beats an older team and it does not wane when they lose a game they were not expected to win. Regarding bad habits, my daughter tends to pick up her dribble to quickly against bigger and faster teams, but as long as she is improving every week I think that this will eventually make her better than her peers.
Overall, I think that teams and / or players should play up to find the right competition level as long as it does not erode confidence. Confidence is the long term key to success.
This past weekend, CC's 4th grade team won both pool play games and entered the elimination round as the 3rd seed. They lost a very close and physical game in the first round.