Delaying kindergarten entry

The Telegraph discusses the problem of "summer born children," who would be younger than their kindergarten peers if enrolled according to the usual school schedule: Does it pay to delay the start of your child's schooling?. The article focuses on the American experience:

"A survey by the US Department of Education in 2007 found that 14 per cent of children aged 5 to 6 had delayed entry into school, or had parents who planned to delay their entry. In some areas - most often those where parents can afford an extra year of pricey pre-school - the level can reach as high as 25 per cent of the classroom.
The practice is more common among boys and tends to be concentrated in some geographic areas, though nearly absent in others. “Middle-class parents are savvy about wanting to know what the trends are and wanting to make sure that their kids aren't outside the norm,” says one education professor.
That's what comes across in a recent post on a parenting blog from an anxious mother in New Jersey. “I am thinking of holding my daughter back so she is emotionally ready for kindergarten,” she wrote, “but I'm also thinking about it because I worry that she will be the youngest since everyone else is holding back.”
“It's pernicious,” says Morrison, who is concerned, as are many other educators, about the effects on the rest of the student body.
Already, teachers must reckon with children who are 12 months apart in age - a big difference when they are just 5 years old. “On every dimension you can think of, you are going to have kids stretched out along a continuum,” says Beth Graue, a former kindergarten teacher, who studies school readiness at the University of Wisconsin. “You've got to accept that you are going to have gigantic five-year-old girls and tiny five-year-old boys who are going to want to do different things.” When some children begin school a year later than their peers, the range - and the challenge for the teacher - is that much bigger."

If schools are tournaments, this could make sense:
"The notion that small differences in age might make a big difference on the field is familiar terrain to Malcolm Gladwell, The New Yorker magazine writer and bestselling author. In his latest book, Outliers: The Story of Success, Gladwell studied ice hockey teams in Canada, where the game is high on the list of national priorities.
By the time kids are just 9 or 10, they are already being selected for elite teams, extra training and top coaching, and at that young age, those born nearest to the January 1 cut-off date - the oldest in each year's grouping - are usually the best, with the extra few months giving them a real advantage on the ice. With more special attention, that advantage seems to stick: Gladwell found that in any grouping of elite hockey players, 40 per cent were born in the first three months of the year. "

This sounds a bit like the reverse of unraveling, the process by which transactions become earlier and earlier in some markets. That process can feed on itself; if everyone else is recruiting early, maybe you had better do so also. It sounds like holding children back from school entry could potentially have the same dynamic: if the other children will all be a year older, maybe you should hold yours back too, especially if you're raising a future football player...