He was a draft-and-follow. Clubs would take flyers on hard to sign guys with low-round picks, but the August 17th signing deadline killed alot of it. Guys would be 'hard to sign' for a # of reasons. A player can be eligible for the draft right out of HS and after their junior and senior year of college, and some are eligible after their sophomore year (pretty sure if they are 3 years out of HS). So with the opportunity to just re-enter the draft, and still develop by playing with their college team, means players can hold out for the bonus they want or for when they feel the time is right to go 'pro'. Lincecum actually passed up signing a pro contract twice- first when the Cubs took him in the 46th rd in '03 and then when the Tribe took a flyer on him in '05.
Matt LaPorta, for example, has been drafted 3 times- the Red Sox in 06 (14th rd) and the Cubs in 03 (14th rd). David Huff was also picked twice before, in '03 and '05. Mark Prior had been previously taken by the Yankees, too.
In Lincecum's case, the Indians used a pick that would have probably been used to fill roster space on a shot at a kid who had an OK season in college but was in the process of destroying the Cape Cod league (a summer wood bat league for top college players). It was a shot in the dark and they didn't get him signed. Another DAF from the same year was a kid named Cody Satterwhite, who went to college and turned himself into a 2nd rounder in 08. One Cape Cod standout who the Tribe did a DAF on who did sign was Tony Sipp, in '04 (also drafted twice prior, in '01 and '02- although as an OFer).
The clubs that really whiffed on Lincecum were the
9 who held picks before the Giants in 06 and didnt' draft him. Egads, now just looking at that list you can tell who really dropped the ball.
