This morning I looked at the 77 players on the American and National League 2013 All-Star rosters. Putting the American and National League results together, we find the following:
Of the 77 2013 All-Stars, 59 (76%) were drafted from the United States, Puerto Rico, or Canada. 26 (34%) of these were from high school, seven (9%) from two-year colleges, and 26 (34%) from four-year colleges. Of the high school guys, I find it particularly noteworthy that only three prep players from California were all-stars this year, and only four from Florida. One of the Floridians (Jose Fernandez) spent much of his life in Cuba. Intuitively, it would seem to me that you would expect more CA and FL players given the scouting resources concentrated in those states.
27 of the 77 players (35%) were first round or supplemental first round picks. 15 more (19.5%) were second round picks. Eleven more were drafted between the third and ninth rounds, and just six in the 10th round or later. Of those six, five came from the college ranks and just one (Domonic Brown) was a high schooler. Two of the college guys (Jose Bautista and Steve Delabar) were a result of the old draft-and-follow rule, so things have changed. Still, for the 2013 class anyway, your best bet to get an impact late-round sleeper in the draft came from the college ranks.
Only seven players this year are from the Dominican Republic. For some reason I thought that number would be higher.
I caution against drawing any wide-ranging conclusions from this survey. This is just one year, and the definition of "All Star" is very broad, encompassing everyone from some solid relief pitchers to genuine superstars without attempting to distinguish them otherwise. It is just a snapshot, but I thought it was worth looking at. It does tend to support previous (and intuitively sensible) research showing that most impact talent enters pro baseball by way of the first two rounds of the draft.