Paceispaceyaar. Immortal words said by Shoaib Akhtar. Pace is pace, friend, mate, brother, pal, machan, boet. Pace. Is pace. There is no substitute for pace. Absolutely no replacement. What it does nothing else can do. You can't buy it in a supermarket, you can't gain it with experience. Years later, Shoaib told the Cricket Monthly he could smell fear. See it in batsmen's eyes. "I would be terrified against my bowling."

Pace like fiyahh, you can hear Michael Holding say in his lovely voice when he sees someone bowl fast. Real fast. Although this is used to say someone's pace is like fire, it can also mean pace itself is like fire. It burns.

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Pace indeed is pace. It is wild, it is thrilling, it is sexy. Pace is power. It is flying stumps, leaping wicketkeepers, hopping batsmen; it is speed guns gone crazy. It is bouncers, yorkers.

Let's slow down and ask a batsman what it is. Says Michael Hussey of extreme pace: "I kind of see it as a bit of a time warp. You see the ball come out of the hand, then you sort of miss a little bit, and then you see it flying past. So when you are facing extreme pace, there is lots of things that go through your mind: getting hurt, how am I going to score, how am I going to react, if I will be able to see it in time."

This is the World Cup of extreme pace, and it is being used in the less glamorous middle overs too. There is nothing else left. The ICC's own data says the average swing this World Cup is as low as in the 2011 one. In that tournament, there was at least turn to be exploited. Bowlers still feel there has been an improvement over what they have had to work with over the last four years. Swing went out of the ODI game just after the last World Cup. There are two balls to be used over 50 overs, which means reverse swing is mostly accidental. Spin, despite the brief surge on account of Southampton, is averaging 47 per wicket.

Bowlers and bowling sides have had to find a way. They have gone to extreme pace.

Paceispaceyaar, but what is pace? What does it mean when you say someone is bowling 145kph? "Means it is bloody quick, mate," a fast bowler says. That's not what you mean to ask, though.

Most cricketers have got their own intuitive speed guns. The metric we see on the big screen is just a supplementary tool for them. It is rare to find a cricketer who knows how this pace is measured. There are various theories that go around: it is an average of speed measured at three (some say even 30) points on the ball's journey from the hand to the batsman, it is measured by dicing the distance by time taken, and so on. None of these theories is true.

The pace figures we get are an imperfect measure. They tell you how fast the ball left the hand of the bowler, not how fast it travelled the distance to the batsman. The first numbers are higher, and thus sexier. Cricketers will tell you that full balls usually register higher on the gun than shorter ones. It has something to do with the trajectory of release. But the batsman will find the short one, which registers as travelling at a lower speed, makes him more uncomfortable. Also, 145kph on a quick pitch is not the same as 145kph measured by the speed gun because the latter doesn't take into account the amount of pace lost upon pitching.

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The biggest imperfection in these numbers can't even be corrected. No machine - yet - can make allowance for different releases. A classical action, like those of Mitchell Starc or Brett Lee, will always seem slower to batsmen than chaotic, imperfect ones - Shoaib Akhtar or Lasith Malinga. A 145kph delivery coming out of a bowler's hand is slower to a batsman than a bowling machine sending out balls at 145kph. That's because they have had the time to watch the ball with the bowler, and they pick it sooner out of the hand.

Release points matter too. The earlier you release the ball, the more time the ball has to lose its speed. Jasprit Bumrah's release is in front of his body; you can easily add 5kph to his readings to get an idea of how fast he must feel to the batsmen. Starc, again, has a classical release - more or less perpendicular to the ground, or even slightly behind the 90-degree mark. Pat Cummins hides the ball a little in the release, so he seems quicker. Lockie Ferguson is similar. So where it matters - batsmen's reactions - Starc will seem slower than what the guns shows, Bumrah will be faster.

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Generally, though, with Bumrah being a big exception, over 145kph - or 90mph - has come to be accepted as extreme pace; the threshold after which it becomes a factor. Hussey feels it is early to mid 150s that got him uncomfortable, but he was in the topmost bracket of batsmen. To Virat Kohli, Joe Root, Kane Williamson and Steven Smith too, the threshold might be early-to-mid 150kph, but on an average, given the variety of batsmen around and tailenders, 145kph is a decent benchmark.

As of June 22, five bowlers - Starc, Jofra Archer, Mark Wood, Ferguson and Kagiso Rabada - had bowled more than 12 balls at over 145kph in this World Cup. That shows you how difficult it is to bowl fast. Everything has to feel right on the day to be able to bowl this fast, but when it does come out quick, the numbers are wonderful.

"That's a big part of my role," Ferguson says. "With the short ball and big square boundaries, use them and put batters under pressure. Because we play on good wickets, we play against the best in the world, and we have done that for a long time. If we can create hesitation with a short ball or a quick yorker, that's the sort of hesitation that might get you a wicket at this level."

Hesitation. As Hussey says, you start thinking: This can hurt. I might not able to time this. Where can I score? Should I stand deeper in the crease? What if the field for the quick bouncer is a bluff?

That's where the fast bowler wants you. Look at the percentage of false shots when the pace goes that high. The overall uncertainty percentage in this World Cup for fast bowlers has been 26%; when it gets above 145kph, batsmen are not in control of 35% to 45% of their shots. Ferguson has drawn false strokes on almost half the deliveries he has bowled at over 145kph.

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"I think for me, if bowlers are bowling over 140, I know the crowd gets behind it," he says. "It's always nice to watch some good pace bowling, some good, aggressive pace bowling in a game that's probably now pretty good as a batter to play on. We play on great [for batting] wickets."

Ferguson and Wood are more effective at this pace because their natural length is short. And short balls register relatively low on the gun, which means a short ball at that pace is really bloody quick. England have broken open at least two innings with precise and quick short bowling. Archer's bouncer to get Faf du Plessis at The Oval was bowled at 149kph. He got Aaron Finch - on 100 - with one at 143kph. Bumrah has used the bouncer excellently, and he doesn't need to register that high on the speed radar.

Starc bowls more balls at extreme pace than anyone else, and draws the least staggering results, which is not surprising. He bowls a lot of yorkers, and they register higher on the speed gun, but also because of his clean action, he is slightly less difficult to react to. This doesn't make him easy to face. His methods are obvious: bowl full and fast. Every third ball he bowls is bowled at over 145kph; every eighth ball is a yorker. That's what makes his wicket of Ben Stokes so special.

Stokes, arguably the best middle-order batsman going around, is set; he is on 89. This is no chancy counterattack but a proper innings. Starc has been brought back to crush the resistance. Everybody knows what is coming. The commentators are talking about it, the crowd is anticipating it, and surely Stokes knows too? And yet, when it does arrive, an inswinging yorker at 149kph, the bat doesn't come down in time. Paceispaceyaar.

We don't get to see the training that goes behind it. Human bodies are not meant to bowl fast. It takes a lot of conditioning to keep doing it. Shoaib says he used to crawl to his bathroom when he woke up. "Every day of my career." Some are more fortunate. Ferguson is. Archer looks effortless. They can undersell the hard work that goes in because they have been injury-free. And even as they undersell, they will throw in a line that gives away their swagger. Ferguson, for example, says: "Lot of fast bowlers will tell you to bowl quick you have to want to bowl quick."

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You need to want to have pace. You have to be mad to be a fast bowler, Shoaib used to say. There are guys who want to have pace, which is why this is the paciest World Cup since the madman, Shoaib, retired.

Admittedly, it hasn't been apparent. Remember we are talking extreme pace in a World Cup where bails are refusing to dislodge. Visually it hasn't looked as sexy as pace is supposed to. As much as it says about the state of pitches, it says a lot about the skill of batsmen too, who prepare for it with extreme-pace throwdowns. Hardik Pandya's Test debut was delayed because he injured himself facing those in the nets.

Nobody is getting blown away. There are no irresistible streaks. Stumps are not flying. Pads are not being blasted off the legs. Catches at fine leg are not what you think of when you think paceispaceyaar. Pace is being used to create hesitation. It is being used to keep teams from getting to 350. A good day for these pace merchants might be 2 for 55 in a score of 320. And yet, four of the five highest wicket-takers this tournament are from this Fearsome Five. Bumrah is neither in that club nor in the top 20 wicket-takers, but his impact is beyond question. These fast bowlers are the most valuable commodity in this World Cup.

Pace is pace, even when it is not paceispaceyaar.