I've been wondering off-and-on about this one for thirty years. Let's say mid-late nineties (pre-Zuffa, post-Davie & Gracie, SEG era UFC). Openweight. Rules of the day. Size advantage for Severn - 1inch of height, 3cm of reach, and probably 30lbs; youth on Frye's side. Severn the better wrestler, Frye the more well-rounded. Common opponents: Ruben "Warpath" Villareal - lost to Severn via SD in 2004, drew with Frye in 2006 and defeated him via KO in 2011. James "The Colossus" Thompson - beat Severn via UD in 2004, beat Frye via TKO in 2007. Mark "The Hammer" Coleman - defeated Severn via submission in 1997, defeated Frye via TKO in 1996 and via UD in 2003. Kenneth Wayne "Shamrock" Kilpatrick - beat Severn via guillotine in 1995 and lost to him via SD in 1996, lost to Frye via SD in 2002. David Lee "Tank" Abbott - lost to Severn via UD in 1995, lost to Frye via RNC in 1996. Samuel "The Experience" Adkins - lost to Severn via sub in 1998, lost to Frye via TKO in 1996. Loser must shave their mustache.
OR, suppose it's 2002 and Severn, instead of going to KOTC, joins his old wrestling student in PRIDE FC and they mix it up there during that stage of their careers. Anything change from six years earlier in the outlaw tourney format?
If anyone initiates the grappling and tries to go for a takedown it would be Severn, but Frye had pretty good takedown defense and was an excellent striker with explosive power. It wouldn't be that easy to take him down, Severn never had the strength of a Mark Coleman.