I’m very suspicious of Jamaica’s recent dominance as well but to say it’s completely unexpected seems a little far fetched to me. They’ve been no worse than the number 4 sprint nation in the world for as long as I can remember (higher if you count ex-pats) and their ex-pats have produced a disproportionate number of sprint champions, indicating that if support and resources are present peoples of Jamaican descent can be world beaters. The fact that many other Caribean nations are very good as well further supports this notion. In fact, I think the Bahamas is the per capita leader when it comes to sprint dominance. And I would guess that any success Ireland has had in the sprints is absolutely dwarfed by the pre-2008 (much less now) Jamaicans both in absolute and per capita terms.