It was early in 2006. Zaheer Khan's career as a Test Match bowler stood at the crossroads. He had been dropped from the Indian Test team for the home series against England, and then for the tour of the West Indies. A new crop of fast bowlers seemed to be emerging for India - Irfan Pathan, RP Singh, Shanthakumaran Sreesanth, Munaf Patel. Munaf made his debut in the second Test against England at Mohali and took 7 wickets.
Zaheer had struggled with fitness upto this point. That is the standard story. Yes fast bowling is strenous activity, but it is anything but pure brute force. I think a better way to put it, about Zaheer and about the other fast bowlers on India's burgeoning fast bowling bench in this decade, is that he didn't know what he was doing in Test Cricket. In order to see this, one would have to set aside the well worn cliches about fast bowlers being slow.
Fast bowling is a very precise art at Test level (as is the case with every other facet of the game). The contest is so refined, and its practitioners are of such high quality, that none of the usual tricks that one assumes a fast bowler must have - a great yorker, a great bouncer, reverse swing, regular swing, a fine seam position, reasonable pace, are enough by themselves. Even genuinely quick bowlers like Shoaib Akhtar and Brett Lee have been in-effective in Test Cricket when their length and line and consistency has been all over the place.
Zaheer's major problem in the first 5-6 years of his career was that he was still learning these things. Unlike bowlers from say Australia or South Africa or England, who get lots of opportunities to become very skillfull fast bowlers even before they play a single Test - Stuart Clark of Australia is a fine example of this and his record shows it, India's fast bowlers come into Test Cricket very raw. The learning curve is steep, and all their skills (the ability to swing the ball, pace, etc.) get stress tested on good (occasionally very flat) wickets against high quality batsmen. As they learn, they inevitably go through the ups and downs which every fast bowler in the history of Test Cricket experiences - they lose a particular type of delivery, they modify their action a bit due to or to prevent injury, all this under the intense pressure of having to win Test Matches.
Only the very best, and only the most resilient, survive. This resilience has to do not just with temperament and determination, it has to do with how well the bowler's skills, and the relative strength of his team, cushion this learning curve. In strong fast bowling line ups, a new bowler may be able to bowl first change, or even with the new ball in a team of three fine fast bowlers, and be shielded from the harshest consequences of bowling at good batsmen, while getting the priceless opportunity to learn in the shadow of his two more illustrious colleagues (see the South African pace attack since their return to Test Cricket as an example). In other cases, there are no clear spearheads.
The great leap that Zaheer achieved in 2006, was to not only improve his fitness, but to begin to put all these other pieces of the puzzle together. He returned to the Test squad for the tour to South Africa in 2006-07, and opened the bowling for India at the Wanderers in Johannesburg in a Test which India won. Zaheer took 5/111 to support Sreesanth's 8/89 and Kumble's 5/54, and also scored a fairly important 37 in an 8th wicket stand of 70 with VVS in the Indian second innings. Since his come back, inspite of playing on many rank featherbeds against very good batting line ups (in India vs Pakistan, Australia and England), Zaheer has managed 87 wickets in 23 Tests at an average of 30.48, and a strike rate of 56. That bowling average is not yet world class, but the strike rate is quite close to being world class, and is 10 balls better than his strike rate in the first 5 years of his career. What is even more striking, is that 64 out of Zaheer's 87 wickets since his come back have been numbers 1-6 in the opposition batting line up. Numbers 1, 2 and 3 make up 44 out of Zaheer's 87 wickets.
Compare Zaheer's record to the most successful fast bowler in the same number of Tests - Dale Steyn (128 wickets in 22 Tests, despite bowling 42 fewer overs than Zaheer). 73 out of Steyn's 128 wickets are top order players, and 39 of 128 are numbers 1, 2 and 3 in the batting line up. Steyn's success against the tail is probably a combination of his extra pace and the fact that he bowls on fast bowler friendly wickets. Steyn is a phenomenal talent - a worthy successor to the great Allan Donald, and will probably surpass White Lightning by the time he's done. Zaheer is harder to score against than Steyn and bowls a slightly higher percentage of his overs as maidens (21% to Steyn's 18%).
The reason behind Zaheer's success in my view, is that he is now a master practitioner of the art of fast bowling. India's first since Kapil Dev (with due respect to Javagal Srinath). His career stats may never look as good as Kapil's let alone Steyn's, but I suspect what you will find is that India will win more series overseas for the rest of Zaheer's career. They have already won (more or less, they could still blow this current one from here) 2 major series thanks to Zaheer.
The devil is in the details. Behind all the talk about "hunger" and "fitness", is the simple fact, that Zaheer knows exactly what he's doing now, where as in his early years he didn't. No other Indian fast bowler since Kapil Dev can claim this. And that has made all the difference.