I am working with some data on NCAA football players. For the purposes of this question, it looks something like this:

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input str25 player_ncaa_pfr int year str22 school_pfr str5 pos_guess_ncaa int(pass_attempts_ncaa carries_ncaa rec_ncaa)
"Rufus Brown"         1999 "North Carolina" "RB"      0  74  2
"Deon Dyer"           1999 "North Carolina" "RB"      0  73  7
"Darrell Jackson"     1999 "Florida"        "WR/TE"   0   2 67
"Travis Taylor"       1999 "Florida"        "WR/TE"   0   0 34
"Shaun Alexander"     1999 "Alabama"        "RB"      0 302 25
"Alex Willis"         1999 "Florida"        "WR/TE"   0   0 24
"Daniel Davis"        1999 "North Carolina" "RB"      0  69  3
"Jason Peace"         1999 "North Carolina" "WR/TE"   0   3 23
"Anthony Saunders"    1999 "North Carolina" "RB"      0  75  2
"Mal Lawyer"          1999 "Clemson"        "WR/TE"   0   0 39
"Brian Wofford"       1999 "Clemson"        "WR/TE"   0   6 60
"Bo Carroll"          1999 "Florida"        "RB"      0  86 10
"Domonique Williams"  1999 "North Carolina" "RB"      0  74  1
"Doug Johnson"        1999 "Florida"        "QB"    337  30  0
"Rod Gardner"         2000 "Clemson"        "WR/TE"   0   4 51
"Andrew Zow"          2000 "Alabama"        "QB"    249  53  0
"Alge Crumpler"       2000 "North Carolina" "WR/TE"   0   0 23
"Jackie Robinson"     2000 "Clemson"        "WR/TE"   0   1 24
"Jesse Palmer"        2000 "Florida"        "QB"    223  36  0
"Brandon Russell"     2000 "North Carolina" "RB"      0 145 11
"Jason McAddley"      2000 "Alabama"        "WR/TE"   0   3 27
"Willie Parker"       2001 "North Carolina" "RB"      0  83  2
"Ronald Curry"        2001 "North Carolina" "RB"      0  89  0
"Andre' Williams"     2001 "North Carolina" "RB"      0 170  5
"Roscoe Crosby"       2001 "Clemson"        "WR/TE"   0   0 23
"Travis Zachery"      2001 "Clemson"        "RB"      0 142 45
"Reche Caldwell"      2001 "Florida"        "WR/TE"   0   5 65
"Freddie Milons"      2001 "Alabama"        "WR/TE"   0   4 36
"Kory Bailey"         2001 "North Carolina" "WR/TE"   0   0 44
"Bosley Allen"        2001 "North Carolina" "WR/TE"   0   0 39
"Robert Gillespie"    2001 "Florida"        "RB"      0  94 41
"Ahmaad Galloway"     2001 "Alabama"        "RB"      0 174  3
"Antonio Carter"      2001 "Alabama"        "WR/TE"   0   0 32
"Andre Williams"      2001 "North Carolina" "RB"      0 170  5
"Jabar Gaffney"       2001 "Florida"        "WR/TE"   0   0 67
"Woodrow Dantzler"    2001 "Clemson"        "QB"    311 206  0
"Rex Grossman"        2002 "Florida"        "QB"    503  58  0
"Yusef Kelly"         2002 "Clemson"        "RB"      0 125 18
"Sam Collins"         2002 "Alabama"        "WR/TE"   0   1 35
"J.J. McKelvey"       2002 "Clemson"        "WR/TE"   0   0 52
"Earnest Graham"      2002 "Florida"        "RB"      0 240 22
"Sam Aiken"           2002 "North Carolina" "WR/TE"   0   0 68
"Tyler Watts"         2002 "Alabama"        "RB"      0 130  0
"Taylor Jacobs"       2002 "Florida"        "WR/TE"   0   3 71
"Santonio Beard"      2002 "Alabama"        "RB"      0 165  5
"Chesley Borders"     2002 "North Carolina" "WR/TE"   0   1 32
"Aaron Walker"        2002 "Florida"        "WR/TE"   0   0 27
"Bernard Rambert"     2002 "Clemson"        "RB"      0 117 11
"Willie Simmons"      2002 "Clemson"        "QB"    244  59  0
"Bobby Blizzard"      2002 "North Carolina" "WR/TE"   0   0 28
"Chad Jasmin"         2003 "Clemson"        "RB"      0 112  7
"Derrick Hamilton"    2003 "Clemson"        "WR/TE"   0  17 62
"Carlos Perez"        2003 "Florida"        "WR/TE"   0   4 36
"Ran Carthon"         2003 "Florida"        "RB"      0 119 21
"Ben Troupe"          2003 "Florida"        "WR/TE"   0   0 39
"Jacque Lewis"        2003 "North Carolina" "RB"      0  61 34
"Triandos Luke"       2003 "Alabama"        "WR/TE"   0   0 32
"Kevin Youngblood"    2003 "Clemson"        "WR/TE"   0   0 70
"Dre Fulgham"         2003 "Alabama"        "WR/TE"   0   1 30
"Shaud Williams"      2003 "Alabama"        "RB"      0 280 24
"Kelvin Kight"        2003 "Florida"        "WR/TE"   0   1 39
"Duane Coleman"       2004 "Clemson"        "RB"      0  83 15
"O.J. Small"          2004 "Florida"        "WR/TE"   0   0 63
"Darian Durant"       2004 "North Carolina" "QB"    299  81  0
"Tyrone Prothro"      2004 "Alabama"        "WR/TE"   0  13 25
"Airese Currie"       2004 "Clemson"        "WR/TE"   0   6 61
"Ciatrick Fason"      2004 "Florida"        "RB"      0 222 35
"Kelvin Grant"        2004 "Clemson"        "WR/TE"   0   0 23
"Ray Hudson"          2004 "Alabama"        "RB"      0  92 11
"Chad Scott"          2004 "North Carolina" "RB"      0 143 13
"Charlie Whitehurst"  2005 "Clemson"        "QB"    340  50  0
"Curtis Baham"        2005 "Clemson"        "WR/TE"   0   0 32
"Mike Mason"          2005 "North Carolina" "WR/TE"   0   1 22
"Reggie Merriweather" 2005 "Clemson"        "RB"      0 149  8
"Brodie Croyle"       2005 "Alabama"        "QB"    339  64  0
"Jon Hamlett"         2005 "North Carolina" "WR/TE"   0   0 21
"Jarwarski Pollock"   2005 "North Carolina" "WR/TE"   0   0 30
"Markus Manson"       2005 "Florida"        "RB"      0  81  9
"Chad Jackson"        2005 "Florida"        "WR/TE"   0  16 88
"Matt Baker"          2005 "North Carolina" "QB"    346  79  1
"Barrington Edwards"  2006 "North Carolina" "RB"      0  91 12
"Jesse Holley"        2006 "North Carolina" "WR/TE"   0   0 37
"Chansi Stuckey"      2006 "Clemson"        "WR/TE"   0   8 50
"Will Proctor"        2006 "Clemson"        "QB"    304  61  0
"Keith Brown"         2006 "Alabama"        "WR/TE"   0   6 44
"Dallas Baker"        2006 "Florida"        "WR/TE"   0   0 60
"Deshawn Wynn"        2006 "Florida"        "RB"      0 143  6
"Kenneth Darby"       2006 "Alabama"        "RB"      0 210 23
"Barrington Edwards"  2006 "North Carolina" "RB"      0  91 12
"Joe Dailey"          2006 "North Carolina" "QB"    195  50  0
"Jemalle Cornelius"   2006 "Florida"        "WR/TE"   0   4 34
"Chris Leak"          2006 "Florida"        "QB"    365  77  0
"Ronnie McGill"       2006 "North Carolina" "RB"      0 192 15
"Rendrick Taylor"     2007 "Clemson"        "WR/TE"   0   2 25
"Kestahn Moore"       2007 "Florida"        "RB"      0 104 13
"Terry Grant"         2007 "Alabama"        "RB"      0 180 26
"D.J. Hall"           2007 "Alabama"        "WR/TE"   0   2 67
"Cornelius Ingram"    2007 "Florida"        "WR/TE"   0   0 34
"Matt Caddell"        2007 "Alabama"        "WR/TE"   0   1 40
"Mike McCoy"          2007 "Alabama"        "WR/TE"   0   0 28
end

I want to rank each player by their position-relevant statistic (passes for QBs, carries for RBs, receptions for WR/TEs) within their position grouping on their team in a given season. For example, in 1999, North Carolina had 5 running backs. I would like my new variable to give Anthony Saunders the rank of 1 since he had the most carries, and Daniel Davis a rank of 5 since he had the least. Meanwhile, North Carolina only had 1 WR/TE in 1999 (in this fake data), Jason Peace, so I would like Jason Peace to get a position rank of 1. And so on...

I tried:
Code:
egen pos_guess_rank_ncaa = rank(pass_attempts_ncaa) if pos_guess_ncaa == "QB", by(school_pfr)
..and then was going to do something similar for the other positions. However, this won't