I know many people get excited about the possibilities on draft day, but perhaps we should remember that the draft is anything but a given. Very rarely do even all Top 5 picks get to the majors, let alone be impact players.
So, doing a quick look at Baseball-Reference's stats, I found out this interesting info:
Last Draft that all Top 5 picks in the first round made the majors: 2006
Last Draft that all Top 5 picks in the first round made the majors AND had a positive career WAR: 1996
Last Draft that all Top 5 picks in the first round made the majors AND had career WAR of 10+: Never (though 1986 was the only time it was very close. 5th pick Kent Mercker had a 9.7 career WAR)
Last Draft that all Top 10 picks in the first round made the majors: 1986 (which is also the only year that has ever happened.)
The 1986 draft was amazing in just getting the top guys to the majors. The first 13 picks all made it to the majors: Jeff King, Greg Swindell, Matt Williams, Kevin Brown, Kent Mercker, Gary Sheffield, Brad Brink, Pat Lennon, Derrick May, Derek Parks, Thomas Howard, Scott Hemond and Ryan Bowen.
Of those, Williams, Brown and Sheffield had pretty decent careers.