Update 2: I thought a bit about it and I came up with a more programmable solution. I am updating the code, I hope you are still following your question. From my point of view this a more correct answer because you are applying 3 times the same command and you force the system to process the command 3 times.

Updated code: Sample of code with command running on my OS

#!/usr/bin/perl
use strict;
use warnings;
use Net::OpenSSH;
use Data::Dumper;

my $host = "127.0.0.1"; # remote IP change
my $port = 22; # ssh default port
my $passwd = "password";
my $user = "username";

my %opts = ( passwd => $passwd, 
         port   => $port, 
         user   => $user );
sub loop {
    my $ssh = Net::OpenSSH->new( $host , %opts );
    $ssh->error and
    die "Couldn't establish SSH connection: ". $ssh->error;

    my @final = ();

    for (1..3) {

    $ssh->system("vmstat") or
        die "remote command failed: " . $ssh->error;

    my @output = $ssh->capture("vmstat");
    $ssh->error and
        die "remote ls command failed: " . $ssh->error;

    push (@final,@output);
    }

    chomp(@final);
    
    return @final;

} # end sub loop

my @array = loop();

print Dumper(\@array);

__END__

procs -----------memory---------- ---swap-- -----io---- -system-- ----
+--cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us s
+y id wa st
 1  0 341104 448888  57136 1158016    5   23    85    85  560 1618 23 
+ 5 71  1  0
procs -----------memory---------- ---swap-- -----io---- -system-- ----
+--cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us s
+y id wa st
 2  0 341104 448504  57136 1158016    5   23    85    85  560 1618 23 
+ 5 71  1  0
procs -----------memory---------- ---swap-- -----io---- -system-- ----
+--cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us s
+y id wa st
 1  0 341104 459728  57136 1147676    5   23    85    85  560 1618 23 
+ 5 71  1  0
$VAR1 = [
          'procs -----------memory---------- ---swap-- -----io---- -sy
+stem-- ------cpu-----',
          ' r  b   swpd   free   buff  cache   si   so    bi    bo   i
+n   cs us sy id wa st',
          ' 2  0 341104 448472  57136 1158016    5   23    85    85  5
+60 1618 23  5 71  1  0',
          'procs -----------memory---------- ---swap-- -----io---- -sy
+stem-- ------cpu-----',
          ' r  b   swpd   free   buff  cache   si   so    bi    bo   i
+n   cs us sy id wa st',
          ' 1  0 341104 459312  57136 1147676    5   23    85    85  5
+60 1618 23  5 71  1  0',
          'procs -----------memory---------- ---swap-- -----io---- -sy
+stem-- ------cpu-----',
          ' r  b   swpd   free   buff  cache   si   so    bi    bo   i
+n   cs us sy id wa st',
          ' 1  0 341104 459568  57136 1147676    5   23    85    85  5
+60 1618 23  5 71  1  0'
        ];
[download]

I am not calculating the average for you I left this part so you can play around and practice a bit. ;)

I execute the code on my localhost so I see double the output because the actual command is executed on my terminal. Which will happen the same on the remote terminal.

Hope this helps, let me know how it worked for you.