Are those full lines? I mean, is this a situation where you can just grab the first and last non-whitespace chars, and just not bother with the stuff in between? ie. does the below code work in your cases, or are there other things that need consideration?

use warnings;
use strict;

while (<DATA>){
    if (/^(\w+).*\s(\w+)/){
        my $line = "$1,$2";
        print "$line\n";
    }
}

__DATA__
SWA vs CHE GK
WBA @ BOU GK
EVE GK
EVE 4 87 dwqer *** GK
[download]

Output:

SWA,GK
WBA,GK
EVE,GK
EVE,GK
[download]