I'd like to tell you a story about two cricketers preparing for a new season. It's a true story, but it's also a parable about success and failure.

The first player gives up almost everything outside cricket. There will be no distractions, he has told himself. He has decided that this will be his breakthrough season; everything else must be relegated to the status of an irrelevant distraction. Cricket is not just the main thing, it is the only thing. He becomes fitter than ever, he spends all his days in the nets and studying televised cricket matches; he even obsesses about the bowlers he will face in the first match, weeks before the game arrives. His quest is to become a machine-like player. He is so eager to learn that he soaks up every piece of advice he can find. Everyone praises his "professionalism".

The second player approaches the season in a more shambolic, human state. He moves house just before the season begins, and spends the first night in his new home without even a lightbulb to help him find his toothbrush. He breaks up with his girlfriend and finds for the first time that he is relying on the warmth of the team life, with its mischief and mickey-taking. Previously he has always been very self-contained; strangely, he is happy to find himself less so. Off the field, he is busy and engaged, having agreed to write a book. The arrival of the season - what season? - comes almost as a surprise, before he is quite in control of his life. He finds that uncertainty - am I ready or not? - energising rather than depressing. Above all, he knows that a life fully lived will make for a good book. He desperately wants to succeed, but he knows that even failure will have its uses.

The first player scores 415 first-class runs at an average of 23. The second player scores 1534 runs at 53. That doesn't prove anything, I hear you say. But what if I told you that they were the same player? It was me - first in 2000, when I dropped off the map as a promising player, then in 2003, when I scored seven hundreds in nine innings and played for England. I learnt my lesson the hard way. I had to feel alive to play cricket properly. I needed a life outside the game to play at my best. The player derives from the man; the man does not emerge from the player.

I am not the only cricketer to have had a purple patch while engaging with life beyond the boundary. Steve Waugh told me that writing a diary coincided with his best seasons. Peter Roebuck produced his best season (1702 runs with seven hundreds) in the year he wrote It Never Rains. Mark Wagh was one of only five Englishmen to score 1000 runs in the first division in 2008, while he was writing Pavilion to Crease… and Back.

And now, best of all, the Tasmania and Australia A opening batsman Ed Cowan has produced a happy ending to top the lot. He kept a diary of his 2010-11 season for Tasmania, now published as In the Firing Line. I'm not spoiling the ending (the scorecard is just a click away on ESPNcricinfo) when I let on that the last page of the book describes Tasmania winning the Shield final. Man of the Match? EJM Cowan, with 133. Both Cowan and his publishers would have settled for that narrative arc when they agreed the deal.

It's also a very good book - honest, analytical, perceptive and brave. You get to know the author and you come to like him. He is not falsely modest, but he looks for the good in others. In years to come, when he reopens his own book, he may find he was a little too generous - but that is all part of the book's warmth and spirit.

What is it about writing a diary that helps cricketers play at their best? You might expect it to lead to over-analysis and too much self-absorption. Paradoxically, writing a diary has the opposite effect: it seems to set cricketers free. Instead of a burden, writing becomes an exorcism

He embraces the tensions that every reflective sportsman must face - between growing up and staying immature, between self-obsession and team-spiritedness, between honesty and denial, between clear-eyed analysis and the wilful illusion of mastery and control.

I couldn't resist a smile of recognition at one inconsistency. Cowan describes his admiration for Nassim Taleb's books on randomness and the power of forces outside our control. Then he goes out to bat in his lucky socks, having had a lucky haircut, eaten at his lucky Italian restaurant, drunk lucky coffee made for him by his wife (did he choose the wife on the grounds that she was lucky, one wonders!). Analytically Cowan understands randomness. In practice, he clings to superstition. Madness? Maybe. Perhaps we all need to be a little bit crazy, especially if you are an opening batsman.

What is it about writing a diary that helps cricketers play at their best? You might expect it to lead to over-analysis and too much self-absorption. Paradoxically, writing a diary has the opposite effect: it seems to set cricketers free. Instead of a burden, writing becomes an exorcism.

There is an even broader point. Every sportsman lives on the knife-edge of outcomes. He either wins or loses, on a daily basis. For the writer, it is very different. All experience, however uncomfortable, contributes to the well of his material. A writer is necessarily an alchemist, and no metal is too dull for him to turn into gold.

Here's a radical thought. Perhaps every sportsman should try to find the pastime that releases him from the tyranny of results. Writing will only work for very few. But almost every athlete, I suspect, would benefit from a complementary challenge of some kind. Michael Bevan told me that once you are a seasoned cricketer, poor form is almost never caused by technical failings. Instead, the root cause is always emotional. So you've got to sort out how you are feeling before the backswing can be corrected.

Professionalism, when it is properly understood, is having the discipline to attend to your whole personality as well as your game. They are, after all, inextricably intertwined - as Ed Cowan has shown us once again.

Former England, Kent and Middlesex batsman Ed Smith is a writer with the Times. His Twitter feed is here