Here is another awk version of that script that's a little more concise and sorts, like the above, using newer features that are in gawk:

  #!/usr/local/bin/gawk -E
  BEGIN{
  	FS=","
  }
  {
  	total_wins[$1]+=$7;
  	total_losses[$1]+=$8;
  }
  END{
  	print "manager,total_wins,total_losses"
  	n = asorti(total_wins, managers)
  	for (i=1; i<=n; i++){
  		m = managers[i]
  		print m "," total_wins[m] "," total_losses[m]
  	}
  }

(I recommend using gawk over mawk or nawk. You might need to install it over the awk that came with your OS.)