In my view, in a game like cricket where the results of a bowler can hinge so much on how well their fielding team mates perform, in the specific instance where a bowler fails to receive a wicket because a catch was dropped, consideration really ought to focus on whether the ball or spell itself deserved a wicket rather than whether the wicket was actually taken or not.
More specifically, I am talking about a situation such as what I've just witnessed tonight, where a bowler (ie. Wahab) bowls a magnificent spell, such as a 6 over delivery that puts tremendous pressure on the batsmen. Eventually, one batsman (Watson) succumbs to the onslaught and mishits the ball to a fielder...
...who drops the catch.
Now, although in this example Wahab did not actually get the wicket, for the purposes of determining who was the best bowler of the night, or who was the Man of the Match, the only fair approach, in my view, is to consider what would have happened had the "dropping" fielder been a competent fielder.
Otherwise it is simply not a fair comparison.
A bowler on another team, for example (Hazlewood), may have received more wickets than Wahab, but that other bowler just so happened to have fielders who did their job properly. That is a completely arbitrary measure. Why should Wahab be labelled as an inferior bowler to any of the Australian bowlers, when he himself did everything right to deserve his wickets, yet was left wanting by his team mates?
Had those catches been caught, Wahab would also have had four wickets. Further to that, Wahab was bowling under pressure when his team had not scored well. Arguably that is performance worthy of a top honour?
By the same token, if Hazlewood bowled the exact same wicket-worthy deliveries but his fielding team mates did NOT catch those balls, does that make Hazlewood a lesser bowler?
Of course not.
All I am saying is that when comparing the quality of the bowlers, one should not merely look to the result (or number of wickets taken); if one is to be fair to all bowlers, careful consideration should be given to whether the wicket would have been taken had the fielders been competent. Only then will you be providing a fair assessment as to who was truly the better bowler of the night.