Just putting everyone's suggestions together by popularity:
QB Kyle Trask - SF Dolphin Fan
QB Mac Jones - Kebo
QB Justin Fields - j-off-her-doll
QB Davis Mills - Fin Thirteen, ckparrothead
QB Brady Davis - ckparrothead
RB Rhamondre Stevenson - SF Dolphin Fan, ckparrothead
RB Trey Sermon - SF Dolphin Fan, Feverdream
RB Elijah Mitchell - Kebo
RB Gerrid Doaks - gregorygrant83
RB Chuba Hubbard - j-off-her-doll
RB Kylin Hill - j-off-her-doll, Fin Thirteen, Feverdream
RB Khalil Herbert - j-off-her-doll
RB Jermar Jefferson - j-off-her-doll
RB Kenneth Gainwell - Feverdream
RB Michael Carter - ckparrothead
RB Javian Hawkins - ckparrothead
RB Brendan Knox - ckparrothead
WR Tamorrian Terry - SF Dolphin Fan, j-off-her-doll
WR D'Wayne Eskridge - SF Dolphin Fan, ckparrothead
WR Dez Fitzpatrick - Kebo
WR Elijah Moore - Gatorboy999120, j-off-her-doll
WR Kadarius Toney - Gatorboy999120
WR Tylan Wallace - Kebo, j-off-her-doll, Fin Thirteen
WR Dyami Brown - dolfan91, j-off-her-doll
WR Anthony Schwartz - gregorygrant83
WR Terrace Marshall - j-off-her-doll
WR Tutu Atwell - j-off-her-doll, ckparrothead
WR Ihmir Smith-Marsette - Fin Thirteen
WR Dazz Newsome - Fin Thirteen
WR Sage Surratt - Fin Thirteen, ckparrothead
WR Amari Rodgers - ckparrothead
WR Austin Watkins - ckparrothead
WR Demetric Felton - ckparrothead
WR Jaelon Darden - ckparrothead
WR Warren Jackson - ckparrothead
WR Josh Imatorbhebhe - ckparrothead
TE Brevin Jordan - j-off-her-doll
TE Tommy Tremble - j-off-her-doll
TE Kenny Yeboah - Fin Thirteen, ckparrothead
TE Tre McKitty - Fin Thirteen
OL Walter Little - SF Dolphin Fan
OL Creed Humphrey - Kebo, j-off-her-doll, ckparrothead
OL Landon Dickerson - Kebo
OL Quinn Meinerz - Kebo, j-off-her-doll, Fin Thirteen, ckparrothead
OL Teven Jenkins - j-off-her-doll
OL Sam Cosmi - j-off-her-doll
OL Aaron Banks - j-off-her-doll, ckparrothead
OL Brady Christensen - Fin Thirteen, ckparrothead
OL Jackson Carman - Fin Thirteen
OL David Moore - Fin Thirteen, ckparrothead
OL Robert Hainsey - Fin Thirteen, ckparrothead
OL Dillon Radunz - ckparrothead
OL Alex Leatherwood - ckparrothead
OL Drew Dalman - ckparrothead
OL Spencer Brown - ckparrothead
OL Sadarius Hutcherson - ckparrothead
OL D'Ante Smith - ckparrothead
OL Matt Allen - ckparrothead
DT Marvin Wilson - SF Dolphin Fan
DT Jaylen Twyman - SF Dolphin Fan
DT Bobby Brown - Kebo
DT Ta'quon Graham - Fin Thirteen
DT Levi Onwuzurike - ckparrothead
DT Daviyon Nixon - ckparrothead
DT Osa Odighizuwa - ckparrothead
DT Payton Turner - ckparrothead
DT Khyiris Tonga - ckparrothead
DT Phil Hoskins - ckparrothead
DE Patrick Jones - SF Dolphin Fan
DE Cam Sample - Kebo, ckparrothead
DE Jayson Oweh - ckparrothead
DE Dayo Odeyingbo - ckparrothead
DE Joshua Kaindoh - ckparrothead
DE Janarius Robinson - ckparrothead
DE Ade Ogundeji - ckparrothead
DE Rashad Weaver - ckparrothead
OLB Elerson Smith - Kebo, Fin Thirteen, ckparrothead
OLB Joseph Ossai - Fin Thirteen, ckparrothead
OLB Chris Rumph - Fin Thirteen
OLB Joe Tryon - Fin Thirteen
OLB Azeez Ojulari - ckparrothead
OLB Quincy Roche - ckparrothead
OLB Daelin Hayes - ckparrothead
LB Paddy Fisher - SF Dolphin Fan
LB Errol Thompson - Kebo, Fin Thirteen
LB Baron Browning - j-off-her-doll, ckparrothead
LB Jabril Cox - j-off-her-doll, ckparrothead
LB Chazz Surratt - Fin Thirteen
LB K.J. Britt - ckparrothead
LB Derrick Barnes - ckparrothead
LB Justin Hilliard - ckparrothead
CB D.J. Daniel - Kebo, ckparrothead
CB Eric Stokes - j-off-her-doll
CB Tyson Campbell - j-off-her-doll
CB Keith Taylor - j-off-her-doll, ckparrothead
CB Tre Brown - j-off-her-doll, ckparrothead
CB Camryn Bynum - Fin Thirteen
CB Paulson Adebo - Fin Thirteen
CB Asante Samuel - silver McNibblets, Nappy Roots
CB Kelvin Joseph - ckparrothead
CB Benjamin St. Juste - ckparrothead
DS Richard Lecounte - Kebo
DS Ar'Darius Washington - SF Dolphin Fan
DS Elijah Molden - j-off-her-doll
DS Jevon Holland - j-off-her-doll
DS Paris Ford - j-off-her-doll
DS Andre Cisco - j-off-her-doll, Fin Thirteen
DS Caden Sterns - Fin Thirteen
DS Talanoa Hufanga - Fin Thirteen
DS Richie Grant - ckparrothead
DS Damar Hamlin - ckparrothead
DS Christian Uphoff - ckparrothead
DS James Wiggins - ckparrothead
Personally I think there are a lot of players I've been talking about for a while that used to be in "steal" territory but now the media have caught up to them.
So here are the ones I think might still be a little underrated.
QB - Davis Mills, Brady Davis
RB - Michael Carter, Rhamondre Stevenson, Javian Hawkins, Brendan Knox
WR - D'Wayne Eskridge, Tutu Atwell, Amari Rodgers, Austin Watkins, Demetric Felton, Jaelon Darden, Warren Jackson, Josh Imatorbhebhe, Sage Surratt
TE - Kenny Yeboah
OL - Dillon Radunz, Creed Humphrey, Alex Leatherwood, Brady Christensen, Quinn Meinerz, Drew Dalman, Spencer Brown, Aaron Banks, Sadarius Hutcherson, Robert Hainsey, David Moore, D'Ante Smith, Matt Allen
DT - Levi Onwuzurike, Daviyon Nixon, Osa Odighizuwa, Payton Turner, Khyiris Tonga, Phil Hoskins
DE - Jayson Oweh, Cam Sample, Dayo Odeyingbo, Joshua Kaindoh, Janarius Robinson, Ade Ogundeji, Rashad Weaver
OLB - Azeez Ojulari, Joseph Ossai, Elerson Smith, Quincy Roche, Daelin Hayes
LB - Baron Browning, Jabril Cox, K.J. Britt, Derrick Barnes, Justin Hilliard
CB - Kelvin Joseph, Keith Taylor, Tre Brown, Benjamin St. Juste, D.J. Daniel
DS - Richie Grant, Damar Hamlin, Christian Uphoff, James Wiggins