Who provides the best bowling assists?
Introducing Assist Percentage - a metric giving a bowler, the deserved credit.
T20 is the closest cricket can get to football. This is a popular comparison, but many parallels are still missed. One such parallel is the focus of today’s discussion. A goal-scorer is usually the most celebrated player when a goal is scored, and crucial assists often never receive the limelight they deserve. Similarly, you often hear commentators saying -
“X bowler probably deserves more credit for that wicket than Y who actually took it.”
These are normally cases where a previous bowler applies pressure and the next bowler reaps the reward. And this is a skill becoming tougher in the modern T20 era, where more pressure is needed now (measured in terms of change in required run rate) to create a wicket opportunity -
Can it be quantified though? Can we know how much has a previous bowler contributed in taking a wicket? We develop something called as the Assist percentage.
THE SETTING
We’re talking only about the second innings here and will be focussing on the effect of an economical over on wicket taking. We classify all previous overs of a wicket taking over in two categories - good and bad. A good over is one where the required run rate increases (rrr at the end - rrr at the beginning is positive). A logistic regression model is then trained to find wicket probability when a previous over creates some rrr difference. The probability values also take the over number into account, because wicket probability generally rises in later overs, favouring death bowlers. The increase in probability (compared to a base probability for every over) is used to calculate the contribution (previous bowler share in a wicket that falls in the next over).
For bad overs, the contribution of the previous bowler is set to 0.
For a fixed required run rate difference, high scoring overs should be less affected as displayed by the regressor when we account for over.
One can understand the situation presented in the graph above by a simple question - If the current probability of a wicket falling is x, then what will increase x more (in percent) - required run rate going from 16 to 18 in the 20th over or rrr going 16 to 18 in the 15th over?
THE BEST ASSISTORS
A wicket is credited as ‘created’ by a bowler if a wicket falls in the following over after he bowls a good over. % Assist is the contribution of that good over towards the wicket (averaged over all occurrences). The discussion above tells us it’s best to compare phase-wise.
Death overs (over 16 to over 20)
Sunil Narine and Rashid Khan are big names there. They lead the pack along with Bumrah in a pacer-dominant phase. One factor though which favours spinners in this list is that they’ll mostly bowl in the first half of this five over phase.
For IPL fans, here’s a more IPL focussed list -
Noor Ahmad is no surprise. He has been trusted with a lot of tough overs in leagues around the world, delivering more often than not. Bumrah actually hasn’t had a lot of quality around him since 2020. Assist by other bowlers in his wickets is 20.48% in 2016-2025, which drops to 15.7% since 2020. Explains a lot probably about MI’s bowling in 2020s.
Powerplay (over 1 to over 6)
Bumrah tops the global list of the last decade. Hardik Pandya, who has now increased his frequency of bowling in the powerplay has proven to be effective as well.
Here’s the IPL focussed list -
Clearly, a metric which rewards defensive bowlers like Santner, who has an incredible 37.26% percentage contribution in wickets taken by a fellow teammate in the PP. An interesting observation on Hazlewood and Curran is that both of them make the top 10 in terms of providing highest assist as well as receiving lowest, suggesting the responsibilities of their bowling attacks have relied heavily on them.
Middle (over 7 to over 15)
I am combining all the remaining nine overs here. The middle overs are as expected spin dominated. Lockie Ferguson is worth mentioning, who tops the charts since 2020 among IPL bowlers. There’s also a certain Glenn Maxwell in the list, whose economy since 2020 in T20s has been 7.63.
Some stat-bites
Among bowlers with 100+ wickets created (after both good and bad over), Bumrah had the best good-over rate delivering 117 good overs before his 144 wicket creations. Among spinners it was Ravi Bishnoi (79 out of 101).
Hazlewood has been the most self - sufficient pacer for his wickets among IPL bowlers, receiving an average assist of only 10.5%. Mujeeb (13.42%) among spinners.
Jofra Archer is the eighth-lowest assist provider (8.67 %) among 188 bowlers with 50+ wickets created in the last 10 years.
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Some damn good insights!
As Arnav comes up with another enticing idea and metric, we wonder why we didn't think of it before. Keep going ... you are opening so many new doors in T20 analytics!