Big boots to fill: Mitchell Johnson.

Big boots to fill: Mitchell Johnson. Photo: AP

Sitting in the visitors' dressing rooms during the  Sheffield Shield match between Western Australia and NSW at the WACA Ground, my gaze was drawn to the honour board that signals those who have taken five or more wickets in a Test innings.

Curtly Ambrose, Michael Holding, Wasim Akram, Richard Hadlee, Shoaib Akhtar and Courtney Walsh are among the luminaries cast in gold – all truly great and enduring fast bowlers of their day. But what makes a great fast bowler?

What do Australia do if he gets injured? 

Australia's latest fast-bowling unit are as successful as they have been unchangeable for the previous six Test matches.

asdad

Illustration: Michael Mucci

But without Mitchell Johnson slinging it down around the 150km/h mark, things could be  different.

Since his 0-60 against India in Delhi at the start of Australia's horror seven-game losing stretch in March last year, he has shaked, rattled and rolled 50 wickets at an average of 13.

Claiming 254 wickets in 57 Tests at an average of 27.5 is good going by Test cricket's bowling gauge, but among that has been a quantum leap in the standard of Johnson's statistics and deliveries since March in Delhi.

Where once he could produce the occasional jaffa, the infrequent unplayable or  discombobulating helmet cruncher, he now produces them almost on demand. The ''once in a generation bowler'' that Dennis Lillee anointed a dozen years ago has taken a big jump towards fulfilling that prophecy.

Players of all specialities love to be in career-best form, it is an elusive and ephemeral state that once entered is not necessarily understood but totally desirable.

Mohammad Yousuf made 1788 Test runs in 2006 when for him making hundreds was de rigueur. Shane Warne had career-best decades and Michael Clarke's 2012 was incomparable. Brad Haddin would love to bottle this summer as well. Maybe he would need two decanters – one each for his bat and his keeping gloves.

Johnson has had a patchy career, one studded with wildness and damage, success and frustration. His technical idiosyncrasies have both provided a catapult for genuine speed and a scattergun style. The one constant, though, has been the ability to bowl with threatening pace and that is a rare and precious commodity.

Fast bowlers capture both wickets and the imagination of the fans. I will never forget the MCG crowd's chant – ''Lil-lee, Lil-lee'' – raising goose bumps when I watched from Bay 13 and then later from mid-off.

It brought inspiration and hope to the supporters and the players.

Finding a simple chant from Johnson's name has come less easily to the home crowds, but the collective roar as he strikes is of the Lillee quality.

Johnson has had an immediate impact on South African crowds and South African batsmen. At times they have both look scared.

Johnson's support crew are of significant quality themselves yet they don't quite evoke the trepidation of Mitch when they are thrown the ball.

Batsmen understand that Ryan Harris or Peter Siddle can produce a delivery that may be too good for them, but they also understand that physical damage is far less likely.

Fear can freeze your thinking and your footwork, neither desirable characteristics for Test batsmen. There is a chasm of difference between losing your wicket and losing your left ear, even if you are wearing a helmet.

The West Indies' quartet of fast bowlers knew exactly how to use fear as a wicket-taking weapon.

Imagine the fear factor with four Mitchell Johnsons lining up at the bowling crease.

Johnson was left out of the winter Ashes series as the selectors couldn't bank on his pressure and accuracy. That was sound judgment based on the home series against Sri Lanka and the failures in India.

There was little or no argument about the correctness of leaving him to work on his limited-overs game.

He did that and found he could swing and control the white ball and thus earned himself a Test recall, not without a little finger-crossing.

With a hardened, 32-year-old body, there now is an expectation he can continue this golden run for a few more years yet, at least past the 2015 Ashes, and then just take it from there.

Brett Lee is one of the few ageing quicks who could maintain high speed. The human body is not keen on being continually placed under maximum stress.

Johnson has been quite simply superb recently, but what do Australia do if he gets injured?

He has been a long time developing to this stage. Where is the next scare merchant and how do we go about developing them?