The record shows Michael Clarke's best position is not a No.3 batsman

Australia's inability to find a permanent and reliable number three batsman under Clarke's reign has made his success as captain all the more remarkable.

The revolving door will continue for the third Test in Perth, when Shane Watson returns from injury to replace Rob Quiney following his pair of ducks in the second Test against South Africa at the Adelaide Oval.

Which begs the question: if the five players used in the pivotal first drop position are collectively averaging just 26 during Clarke's 16 Tests in charge and he is averaging a whopping 75, why doesn't he simply move up the order?

That argument is not as simple as it sounds.

In many cases there is a clear distinction between top order players, who bat in the first three, and middle order players, who bat from four to six.

Clarke is currently 11th on Australia's list of all time run scorers and the top 10 is almost evenly split.

Ricky Ponting is on top as Australia's most prolific top order player while second-placed Allan Border preferred to bat from four to six and third-placed Steve Waugh spent the majority of his career at five.

There is no argument that Clarke's best place is at five or six because that's what the figures show.

He averages 21 at number four, 63 at five and 50 at six.

But the reasoning goes well beyond simple statistics. Clarke is the best player of spin in the team.

His sharp footwork and deft hands allow him to work or stroke the ball from the outset.

Things could change if Ponting does not make it beyond the next Test in Perth, as his current form suggests.

Clarke may then be forced to move up to at least number four, although that appears unlikely.

The most obvious replacement candidates for Ponting are top order players Phil Hughes and Usman Khawaja, who would be best suited slotting in at three with Watson coming in at four.

The traditional view is that all-rounders should bat at six because they also bowl does not hold with Watson.

A wonderful striker of the ball, Watson is better against the new ball with the field up. The further up the order he bats the better.

Follow the J curve of his innings and it almost always shows that Watson starts well and slows down as the field spreads.

Heavy-footed, he is not a great runner between wickets and can struggle to rotate the strike, which helps to explain why he fails to turn fifties into hundreds.

Playing Watson as low as four would not be ideal given his best place is probably opening the batting but with a century each in the first two Tests of the summer, Ed Cowan and David Warner have nailed down their spots.

The bottom line is Australia needs to find a more functional and stable top order than the one that has left it three wickets down for under 100 16 times in the past 16 Tests.

N0. 3 since Clarke became captain:

Ricky Ponting: 48 runs in one Test at an average of 24
Shaun Marsh: 301 runs in seven Tests at 27
Usman Khawaja: 145 runs in three Tests at 29
Shane Watson: 193 runs in three Tests at 32
Rob Quiney: Nine runs in two Tests at 3
Total: 696 runs in 16 Tests at 26