for my $file ( @files ) {
    ( $basename ) = ( $file =~ /(.+)\.txt$/ );
    if ( open( F, $file )) {
        ( $date, @values ) = <F>;
        chomp $date;
        chomp @values;
        s/.+?,// for ( @values );      # delete the "name," parts
        print join( ",", $basename, $date, @values ), "\n";
        close F;
    }
    else {
        warn "$file: $!\n";
    }
}