Guess what? High 4 and 5 star WR talent (NFL prototypes) most likely won't sniff Nebraska, cuz we've put what, one guy in the NFL at that position (Fryar).
It's not necessarily about what Nebraska has put in the NFL, but how Nebraska will be using them under this staff.
For reference, here is a list of Nebraska players selected as WRs in the NFL draft:
Year: Rd-Pick (Overall Pick) Name, Team, Pos (Notable professional contributions)
1966: 9-07 (132) Freeman White, New York Giants, WR (5 professional seasons, 4 with NYG)
1973: 1-25 (25) Johnny Rodgers, San Diego Chargers, WR (Played in CFL for 4 seasons as an all-star, then 2 in San Diego)
1974: 10-01 (235) Frosty Anderson, New Orleans Saints, WR
1975: 6-1 (131) Don Westbrook, Baltimore Colts, WR (5 seasons in New England)
1975: 14-20 (358) Ritch Bahe, St. Louis Cardinals, WR
1979: 10-16 (264) Frank Lockett, Green Bay Packers, WR (6 professional seasons across USFL and NFL)
1980: 3-23 (79) Tim Smith, Houston Oilers, WR (7 seasons with Houston: 206 rec, 3107 yds)
1980: 10-09 (258) Ken Brown, Minnesota Vikings, WR
1981: 9-14 (235) John Noonan, Miami Dolphins, WR
1983: 6-14 (154) Todd Brown, Detroit Lions, WR
1984: 1-01 (1) Irving Fryar, New England Patriots, WR (17 NFL seasons: 851 rec/44 rush, 13,027 scrimmage yds, 85 TDs, 5 pro bowls)
1985: 12-07 (315) Shane Swanson, Cleveland Browns, WR
1988: 11-23 (300) Hendley Hawkins, Cleveland Browns, WR
1989: 8-09 (204) Dana Brinson, San Diego Chargers, WR
1992: 7-25 (193) Jon Bostick, Denver Broncos, WR
2001: 6-03 (166) Bobby Newcombe, Arizona Cardinals, WR
2002: 3-30 (95) Eric Crouch, St. Louis Rams, WR (sort of)
2011: 5-23 (155) Niles Paul, Washington Redskins, WR (6 seasons with Washington, moved to TE and still active)
2014: 6-33 (209) Quincy Enunwa, New York Jets, WR (4 seasons with NYJ, still active)
2015: 5-26 (162) Kenny Bell, Tampa Bay Buccaneers, WR (3 seasons on practice squads, currently with Denver)
Among current players, I'd assume Morgan and Spielman will get drafted.
You're right, not a lot of career studs outside of that #1 overall pick in 1984. It's also a function of the systems that were run at NU. That doesn't mean it can't happen.
For comparison, here are the Oregon players drafted as WRs:
Year: Rd-Pick (Overall Pick) Name, Team, Pos (Notable professional contributions)
1971: 7-16 (172) Bob Newland, New Orleans Saints, WR (4 seasons with New Orleans: 124 rec, 1877 yds, 8 TDs)
1972: 8-08 (190) Leland Glass, Green Bay Packers, WR (2 seasons with Green Bay)
1972: 1-04 (4), Ahmad Rashād (aka Bobby Moore), St. Louis Cardinals, WR (10 seasons, 4 Pro Bowls: 495 rec/10 rush, 6883 scrimmage yards, 44 TDs)
1980: 8-04 (197) Don Coleman, Denver Broncos, WR (2 seasons with New Orleans)
1986: 5-28 (138) Lew Barnes, Chicago Bears, WR (3 seasons, bounced around as a return man)
1988: 8-23 (216) J.J. Birden, Cleveland Browns, WR (9 seasons, mostly with KC: 244 rec, 3441 yds, 17 TDs)
1998: 2-12 (42) Patrick Johnson, Baltimore Ravens, WR (7 seasons, mostly with Baltimore: 84 rec, 1286 yds, 10 TDs)
2003: 7-07 (221) Keenan Howry, Minnesota Vikings, WR (3 seasons with Minnesota, still in the CFL)
2004: 4-09 (105) Samie Parker, Kansas City Chiefs, WR (4 seasons with KC: 110 rec, 1529 yds, 7 TDs)
2005: 7-09 (223) Marcus Maxwell, San Francisco 49ers, WR (not much to report, bounced around various leagues for a while)
2006: 4-14 (111) Demetrius Williams, Baltimore Ravens, WR (5 NFL seasons, 4 with Baltimore: 63 rec, 1008 yds, 4 TDs)
2007: 6-36 (210) Jordan Kent, Seattle Seahawks, WR (2 NFL seasons, 1 reception)
2014: 3-22 (86) Josh Huff, Philadelphia Eagles, WR (3 NFL seasons, didn't play in 2017, now with New Orleans but currently suspended by the NFL: 83 rec, 523 yds, 4 TDs)
From the time Frost was at Oregon (2009-2015; 2009-2012 WR, 2013-2015 OC/QB), they only had one WR drafted into the NFL. But I'm sure we'd accept Oregon's success during that span.
As others have pointed out, with this staff, it isn't about the stars necessarily, but finding players with speed who can develop into tools for the system. Once Nebraska starts winning some games on a bigger stage, then you'll see stars interested. I'm optimistic that'll happen one day, and also content for now with the staff's ability to find diamonds in the rough and develop. Ryan Held feasts on that, as another poster pointed out in a different thread. He's had to working at Division 2 and JUCO schools.
Here is Oregon's recruiting (Rivals) during Frost's time there...
2009: #32 Team Ranking
(2) 4-star, (1) 3-star, (2) 2-star WRs
Nick Cole, WR, Concord, CA, 6'3", 185, 5.2 **
Tyrece Gaines, WR, El Dorado, KS, 6'2", 225, 5.9 ****
Braxton Lane, WR, Tyrone, GA, 5'10", 187, 5.4 **
Diante Jackson, WR, Walnut Creek, CA, 6'0", 188, 5.8 ****
Lavasier Tuinei, WR, Huntington Beach, CA, 6'6", 195, 5.6 ***
Zero RBs and ATHs taken recruited this class.
2010: #13 Team Ranking
0 WRs taken in this class
4-star Josh Huff and 5-star Lache Seastrunk were recruited as RBs.
4-star Keanon Lowe recruited as an athlete.
2011: #9 Team Ranking
(3) 4-star, (1) 3-star WRs
B.J. Kelley, WR, Fresno, CA, 6'2", 175, 5.6 ***
Devon Blackmon, WR, Fontana, CA, 6'0", 175, 6.0 ****
Rahsaan Vaughn, WR, San Mateo, CA, 6'2", 190, 5.8 ****
Tacoi Sumler, WR, Miami, FL, 5'8", 151, 5.8 ****
5-star De'Anthony Thomas was recruited as an athlete.
2012: #16 Team Ranking
(2) 4-star, (1) 3-star WRs
Chance Allen, WR, Missouri City, TX, 6'3", 191, 5.6 ***
Bralon Addison, WR, Missouri City, TX, 5'10", 182, 5.8 ****
Dwayne Stanford, WR, Cincinnati, OH, 6'5", 185, 5.8 ****
4-star RB Byron Marshall and 3-star ATH Oshay Dunmore recruited in this class.
2013: #22 Team Ranking
(2) 4-star WRs
Devon Allen, WR, Phoenix, AZ, 6'1", 190, 5.8 ****
Darren Carrington, WR, San Diego, CA, 6'2", 187, 5.8 ****
5-star Thomas Tyner and 2-star Kani Benoit recruited at RB.
4-star Tyree Robinson, 4-star Tyrell Robinson, and 3-star Chris Seisay recruited as ATHs.
2014: #26 Team Ranking
(1) 4-star WR
Jalen Brown, WR, Phoenix, AZ, 6'2", 183, 5.9 ****
4-star Tony James and 4-star Royce Freeman recruited at RB.
3-star Charles Nelson recruited as an athlete.
2015: #17 Team Ranking
(2) 4-star WRs
Kirk Merritt, WR, Destrehan, LA, 5'11", 203, 5.8 ****
Alex Ofodile, WR, Columbia, MO, 6'1", 201, 5.8 ****
4-star Malik Lovett and 4-star Taj Griffin recruited at RB.
Oregon had solid recruiting during Frost's time as an assistant. But they have also had a recent 7-year drought of WRs being drafted into the NFL: only 1 WR drafted during (and as of now, after) Frost's time at the school. And they were a good if not great team during that time.
EDIT: I apologize for the long post, I definitely went down the rabbit hole this morning.