In 2004, the Colorado Rockies had the 9th overall pick in the draft. They decided to draft infielder Chris Nelson with that pick. He spent parts of five seasons in the major leagues as he played in 282 games, 212 of them with the Rockies. He only played in more than 64 games in a season once and in his career, he had a WAR of -2.4.
Here are some of the notable first round draft picks after Nelson.
Neil Walker*: second baseman (drafted as a catcher), 11th overall pick, 10 year MLB career, 20.2 WAR, 131 home runs, 535 RBI, .270/.340/.432, 112 OPS+, one-time Silver Slugger Award winner
Jered Weaver: right-handed pitcher, 12th overall pick, 12 year MLB career, 34.4 WAR, 150-98 record, 3.63 ERA, 111 ERA+, three-time All Star, ranked in AL Cy Young Award voting three times (including a second and third place), ranked in AL MVP voting once
Billy Butler: 1st baseman/outfielder, 14th overall pick, 10 year MLB career, 11.6 WAR, .290/.354/.441 slash line, 116 OPS+
Stephen Drew: infielder, 15th overall pick, 15th overall pick, 12 year MLB career, 17.1 WAR, 123 home runs, 524 RBI, .252/.318/.423, 94 OPS+, ranked in MVP voting once
Gio Gonzalez*: left-handed pitcher, 38th overall pick, 11 year MLB career, 27.1 WAR, 122-88 record, 3.60 ERA, 113 ERA+, two-time All Star, ranked in NL Cy Young Award voting twice, ranked in MVP voting once.
Huston Street: right-handed pitcher, 40th overall pick, 13 year MLB career, 2.95 ERA, 141 ERA+, 324 career saves, two time All Star, ranked in MVP voting twice, 2005 AL Rookie of the Year Award winner
There are a lot of successful MLB players who were in later rounds of the draft including Yovani Gallardo*, Hunter Pence*, Dustin Pedroia*, Jason Vargas*, current Rockie Wade Davis*, (much to the chagrin of Rockies fans) current Rockie Ian Desmond* (cue the boos), J.A. Happ*, current Rockie Chris Iannetta*, current Rockie Jake McGee* (lots of future Rockies), former Rockies Dexter Fowler* and Mark Reynolds*, Lorenzo Cain*, Mark Trumbo*, David Price*, current Rockie Mike Dunn*, Todd Frazier* (who the Rockies drafted but didn’t sign), Jake Arrieta* (who didn’t sign), and Chris Davis* (who didn’t sign).