Four days before the Raiders begin arriving in Napa for training camp -- and eight days before the first padded, i.e., hitting practice on Aug. 1 -- Oakland was still one of nine NFL teams with at least one unsigned draft pick.In fact, Tuesday afternoon the Raiders were one of six teams with at least two of their draftees still unsigned in third-round supplemental pick Tony Bergstrom, the offensive lineman from Utah who went No. 95 overall, and fifth-round supplemental pick Juron Criner, the offseason workout program revelation at receiver who was picked 168th overall out of Arizona. And there does not seem to be any notable progress in talks.Adam Caplan of thesidelineview.com broke down the 16 unsigned rookies thusly -- five first-rounders, two second-rounders, eight third-rounders, with Bergstrom at the end of that round, and one fifth-rounder, which is Criner.As such, Bergstrom and Criner are the lowest-drafted rookies still unsigned in the NFL.So is it something for Raiders fans to worry about yet?Why they remain unsigned remains a mystery to most observers and has the potential to become an irritant to the team and first-year general manager Reggie McKenzie. Especially since the two rookies' salary is all-but slotted courtesy of where they were drafted.Documents obtained by CSNCalifornia.com show that Bergstrom would have a first-year allotment of 516,504 with a first-year minimum allotment of 512,504 and non-guaranteed base salaries of 390,000, 480,000, 570,000 and 660,000 on his four-year contract with a maximum signing bonus of 506,016. Criner, meanwhile, would have a first-year allotment of 426,140 with a first-year minimum allotment of 422,140 and non-guaranteed base salaries of 390,000, 480,000, 570,000 and 660,000 on his four-year contract with a maximum signing bonus of 144,560.So what's the holdup?Per Caplan, the Miami Dolphins had the most unsigned draft picks Tuesday afternoon with three, followed by the Raiders (2), Minnesota Vikings (2), Jacksonville Jaguars (2), Indianapolis Colts (2), St. Louis Rams (2), Cincinnati Bengals (1), Kansas City Chiefs (1) and Tennessee Titans (1).