# Slower balls in IPL: Perfect Strategy & Mustafizur the Freak

### What is the ideal slower ball strategy? Who does it best? We look at the numbers

Whether it’s off-cutters, leg-cutters, knuckleballs, palm balls, split-finger deliveries, or back-of-the-hand deliveries, variations in pace have never been more popular than they are today. Along with the aforementioned types of speed variations, different bowlers opt for different lines and lengths in their efforts to deceive and often dismiss batters.

So, who have been the most skilled exponents of speed variations in the IPL since 2019? And what is the best slower ball strategy in T20 cricket?

To answer these questions, let’s take a look at the numbers from the last few seasons of the IPL.

*NB: For the intents and purposes of this article, a slower ball is classified as any delivery which is less than or equal to 90% of the 80th percentile of a bowler’s speed.*

**Masterful Mustafizur**

Out of all bowlers who’ve bowled a minimum of 75 slower balls since IPL 2019, nobody has bowled a higher percentage of their total deliveries as “slower” than Mustafizur Rahman at 48.1%. Unsurprisingly, the next highest slower ball percentage (42%) belongs to Lasith Malinga, the greatest fast bowler to have graced the shortest format of the game.

While Malinga’s slower ball strike rate of 9.7 is the third-best — marginally behind Chris Morris and Trent Boult — his ability to restrict batters has waned towards the tail end of his career.

Mustafizur has had no such issue.

The Royals’ left-armer bowls slower deliveries more frequently and more economically than anyone else, yet he still manages to pick up wickets more often than most regular slower ball bowlers. His slower ball economy rate of 6.71 is comfortably ahead of second-placed Jasprit Bumrah, who concedes 6.97 runs per over, but his strike rate of 12.7 is almost twice as good as Bumrah’s 25.3.

If we plot the slower ball economy rates of bowlers against their strike rates since IPL 2019, you will find the best users of speed variations in the bottom left of the graph.

Punjab Kings’ Arshdeep Singh deserves a special mention. He has struck slightly more frequently than Mustafizur Rahman in recent times while being one of only three bowlers to maintain an economy of less than 8—7.1 to be more precise. Remarkably, he has allowed Punjab to compensate for their failure to recruit a quality overseas quick, especially one capable of finishing the innings.

Proteas fans clamouring for Chris Morris’ inclusion in South Africa’s World Cup squad should look away now. The Royals all-rounder strikes every 9.4 deliveries with his slower changeups, conceding just a shade above 8 runs an over.

At 9.3, Trent Boult may have the best slower ball strike rate, but the Kiwi quick is also the second-most expensive, conceding an eye-watering 11.43 runs an over. Mohammad Shami concedes 11.47 runs per over, but his middle-of-the-pack strike rate ensures that Ben Stokes occupies the lonely top-right of the scatter plot.

**Harshal the Dark Horse**

RCB’s Harshal Patel, another uncapped Indian, is also close to the bottom left corner of the scatter plot. He strikes every 10.1 deliveries, conceding 8.18 runs per over, which is the sixth-best slower ball economy rate since IPL 2019.

Let’s take a deeper look at how he’s pulled this off.

Harshal (13%) and Dwayne Bravo (15%) have bowled a higher proportion of their slower ones as yorkers compared to any other quicks since IPL 2019.

However, they differ in one key element: the spread of their slower ball speeds. Bravo has the second-highest standard deviation of any bowler at 6.1 kmph, marginally behind Jofra Archer at 6.2. Harshal Patel, on the other hand, has the narrowest range of speeds with his slower deliveries.

In spite of this, his slower ball statistics dwarf Bravo’s numbers since 2019. Bravo has conceded 9.79 runs an over since 2019, taking a wicket roughly every 22 balls. One possible reason for this could be that Bravo has simply overpitched and under-pitched his attempted slower yorkers more often than the uncapped Indian. According to data available since IPL 2015, missed slower yorkers that end up as either full tosses or overpitched slot balls allow batters to strike at 171.

As many have observed, a standout feature of Harshal’s 29-wicket season thus far has been the deviation he gets on his slower deliveries. While he doesn’t possess a large range of slower ball speeds, he’s gotten more left to right deviation than any other bowler since 2019.

Mustafizur, unsurprisingly, is up there with Harshal as the bowler with the greatest right to left deviation since 2019, which further explains his chart-topping economy rate.

**Best Slower Ball Length and Line**

Now that we have established the best slower ball bowlers in the IPL in recent times, let’s look at the best lines and lengths to employ when bowling slower balls in T20 cricket based on data collected since from IPL 2015 onwards.

Slower balls delivered on a very short length — defined as more than 9 meters away from the batting crease — average 25 and allow batters to strike at 156.

A more economical option is bowling slower deliveries on a hard length between 7 and 9 meters away from the batting crease. This only allows batters to strike at 138 while averaging 27.

The caveat here is that if you miss the hard length and bowl it on a good length between 4.5 and 7 meters from the batting crease, batters will be able to strike at 161.

A better option, although far from optimal, is to bowl it very full between 3 and 4.5 meters away from the batting crease, which restricts the average batters’ strike rate to 152.

Without a doubt, the best length to hit if you want the best results from your slower ball is the yorker. Batters only average 18 against slower yorkers, while striking at a mere 106.

If, however, you are unable to nail your yorkers, opting for a hard length is the next most economical approach even if it is suboptimal on average.

**What about line?**

The data since supports the notion that you shouldn’t give batters the width to free their arms. The strike rate for batters facing hard length slower balls bowled at the stumps is 132 compared to 152 for those delivered wide.

But the prize for perfect slower ball goes to…

Wait for it.

The slower yorker at the stumps!

This freak of a delivery only allows batters to average 9.5 and strike at 101. The slower yorker at the stumps will take a wicket roughly twice as often as the average slower yorker and more than twice as often compared to all yorkers regardless of length, line and pace. The average yorker will also allow batters to strike 10 points higher at 111.

At this point, you may be questioning if it is worth bowling a slower yorker given the perceived difficulty. What if things go wrong?

Let’s tackle this concern by looking at what happens when you miss the average yorker regardless of pace versus missing slower yorkers.

The average missed yorker allows batters to strike at 184. The corresponding figure for slower yorkers dips to 171, and even further to 163 for straight slower yorkers. The deception and often the dip involved in attempted slower yorkers can act as an insurance policy even if a bowler misses their lengths.

So, if you’re a bowler who wants to shield yourself from an onslaught, practice bowling slower ones at a batter’s feet. Even if it does go wrong, it will on average, go less wrong than if you hadn’t varied your pace.

**So what does this all mean?**

Like many analysts have noted, the IPL is not like Major League Baseball, where each team plays a whopping 162 games during the regular season. The comparatively smaller pool of data on specific bowlers should not be misconstrued as timeless truths about their pedigree.

However, one thing is for sure: you do not have to bowl at express speeds to be a dangerous T20 fast bowler. On the contrary, success is often determined by what you do when you’re not bowling fast.

##### Header Image: Rajasthan Royals Twitter

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