No one can be designated as a player to be named later unless they're eligible to be dealt. In other words, 2015 draftees can't get tagged as a PBTNL until the end of this year's Fall Classic. For the previous 29 Drafts, assuming a player signed in June, he could be tabbed as a PTBNL in December and switch organizations six months after that. (PTBNL rules provide up to six months for the player to be actually named.)
The Padres selected Turner with the No. 13 overall pick in the 2014 Draft and signed him for $2.9 million on June 13. He hit .323/.406/.448 with 23 steals in his 69-game debut at two stops in Class A last year, establishing himself as one of baseball's best shortstop prospects. Turner currently ranks No. 61 on MLBPipeline.com's Top 100 Prospects list.
When San Diego general manager A.J. Preller saw an opportunity to acquire Wil Myers from Tampa Bay this past offseason, he pounced. In a three-team, 11-man trade on Dec. 19, the Padres got Myers and three other players, the Rays landed Steven Souza and four other players, and the Nationals received two of San Diego's best prospects: a player to be named later (widely known to be Turner, though the teams won't confirm this) and right-hander Joe Ross.
Turner couldn't officially be part of the deal until nearly six months after it was consummated, forcing him to stay in limbo as part of the Padres' farm system. Fortunately for him, his development hasn't been stunted. He's playing regularly at Double-A San Antonio, where he's hitting .282/.354/.408 with two steals in 18 games.
For the first 20 years of the Draft, teams could trade draftees whenever they desired. Then, in 1985, the Expos drafted Oklahoma State slugger Pete Incaviglia eighth overall in arguably the best talent pool in Draft history. Incaviglia, who set still-standing NCAA records for single-season (48) and career (100) homers, wanted no part of playing in Montreal.
Incaviglia held out all summer and refused to sign until November -- and then only if the Expos would immediately trade him to the Rangers. Clubs didn't get a compensation pick for an unsigned first-rounder back then, so Montreal had little leverage.
The Expos sent Incaviglia to Texas for Bob Sebra, who won 15 games in six big league seasons, and Jim Anderson, who never again played in the Majors. Incaviglia hit 30 homers in 1986 as a rookie with the Rangers and totaled 206 in a 12-year big league career.
As a response, MLB made two changes to the Draft rules. Starting in 1986, teams couldn't deal a player until one year after he signed his first pro contract, and they also received a supplemental first-round choice in the next Draft if they failed to land their first-rounder. (Beginning with the 2007 Draft, teams that didn't sign a pick in the first two rounds got the choice after the corresponding selection in the next Draft; clubs that didn't ink a third-rounder got a supplemental third-rounder.)