Harps is a slightly lesser bowler than Diggler but he can bowl longer spells and add useful lower order runs, plus he's at an earlier point in his career and will improve more. Diggler is the sidekick.
Haha I went out to have some tea after the first innings (and 400 run lead for Kittens). Now imagine my surprise when I came back and saw a 'WIN!' besides Brumbies' name.