Fast bowlers, side by side

Illustrative analysis. Independent technical commentary by BatSwing, built from short excerpts of broadcast and social clips. Not affiliated with or endorsed by the players, any board or any broadcaster. Qualitative only: no angles, no speeds, and no view on whether any action is legal.

Batting has a vocabulary coaches share: stance, backlift, stride, impact, follow-through. Fast bowling has one too. This post uses it to read four actions (Bumrah, Starc, Archer and Steyn), then looks at where Bumrah and Wood landed the ball. It works one camera at a time, and is honest about what each camera can and can’t show.

The bowlers, and the footage each one comes from:

Bowler	Footage	Camera
Jasprit Bumrah	Australia v India Test, broadcast replay	Side-on, slowed
Mitchell Starc	Australia v India white-ball match, broadcast replay	Side-on, slowed
Jofra Archer	Nets session, social clip	Front-on, slowed
Dale Steyn	Nets session, social clip by Free Life Official	Front-on, slowed
Jasprit Bumrah	ECB official highlights, England v India	End-on, live speed
Mark Wood	ECB official highlights, England v Australia	End-on, live speed

Every skeleton below is an automatic 2D estimate from a pose model, drawn on the video with the bowling arm in green and the picture behind it dimmed. The key moments (back-foot contact, front-foot contact and release) were marked by eye, frame by frame, and checked by hand; the frames in between were picked to show the shape. They are pictures to talk about, not measurements. Four of the clips are slowed replays, so nothing here says anything about timing.

One delivery in one picture

A fast bowler’s delivery stride takes well under a second. Stack the frames and you can see its shape: the bound, the back foot landing, the front foot landing, the arm coming over, release and the follow-through.

Mitchell Starc cut out of six frames of one delivery and set side by side on a plain background: the bound, back foot landing, front foot landing, the arm coming over, release and the follow-through. — Mitchell Starc, left-arm: the bowler cut out of six frames of one delivery and set on a plain background. The figures are in order along the run-up, but the gaps are not to scale: where two would hide each other, the later one is moved along. Footage: Australia v India white-ball match, broadcast replay.

The six moments, bowler by bowler

Each strip below is one delivery, cropped around the bowler. The green frames are the two moments a coach looks at first: front-foot contact and release. On a phone, swipe a strip sideways to see all six frames.

Jasprit Bumrah's delivery stride in six frames: bound, back-foot contact, front-foot contact, arm coming over, release and follow-through. — **Jasprit Bumrah**, right-arm. Side-on, panning camera. Footage: Australia v India Test, broadcast replay.

Mitchell Starc's delivery stride in six frames: bound, back-foot contact, front-foot contact, arm coming over, release and follow-through. — **Mitchell Starc**, left-arm. Side-on. Footage: Australia v India white-ball match, broadcast replay.

Jofra Archer bowling in the nets, filmed front-on, in six frames from the bound to the follow-through. — **Jofra Archer**, right-arm. Front-on from behind the stumps in the nets. His hand is above the top of the frame at release, so the fifth frame is around release, not on it. Footage: nets session, social clip.

Dale Steyn bowling in the nets, filmed front-on, in six frames from the bound to the follow-through. — **Dale Steyn**, right-arm. Front-on in the nets. Footage: Free Life Official, social clip (the watermark is theirs).

Put the two side-on strips together and the actions look nothing alike. Bumrah’s bound is short, with both arms spread wide. Starc’s gather is longer and more flowing. Yet at front-foot contact both have the front arm out towards the batter and the bowling arm back behind them, about to come over. Different routes, a shared middle.

From in front, Archer and Steyn show what side-on hides: how the bowler lines up with the stumps, and how close to the head the bowling arm comes over.

What the front leg does

Between front-foot contact and release, the front leg can stay firm while the body goes over it (coaches call that a braced front leg), give a little (softens), or fold as the body sinks into it (bends). You can see which side-on without a single number.

Bumrah from front-foot contact to release in three frames, front leg in green: it stays almost straight, giving a little by release. — Front-foot contact, a frame between, and release, with the front leg in green. Bumrah's leg stays almost straight and gives a little by release; Starc's knee gives more. Both are proposed reads from the 2D skeleton, in words, not a coach's call. Footage: broadcast replays, Australia v India (Test for Bumrah, white-ball for Starc).

Starc from front-foot contact to release in three frames, front leg in green: the knee folds as he goes over it. — Front-foot contact, a frame between, and release, with the front leg in green. Bumrah's leg stays almost straight and gives a little by release; Starc's knee gives more. Both are proposed reads from the 2D skeleton, in words, not a coach's call. Footage: broadcast replays, Australia v India (Test for Bumrah, white-ball for Starc).

Bumrah's delivery with traces drawing in as he bowls: the bowling wrist's path (white, with release as a green dot), the head's path (dotted), the front leg from front-foot contact to release and the footprints. Where his arm passes behind his body the pose model briefly loses the wrist; gaps of a few frames are joined and drawn dashed, and a longer gap would stay a break. Slowed down. Footage: Australia v India Test, broadcast replay. About eight seconds, no sound.

Neither is “right”. A braced front leg is common among the quickest bowlers, and a softer one is common too. What matters for a coach is whether a bowler does the same thing ball after ball, and whether it changes when they’re tired.

The two front-on clips get no front-leg read at all. From in front, a straight leg and a bent one can look the same, so the honest answer is “needs a side-on camera”.

Release

At the 25 to 30 frames a second of most of these clips, the ball leaves the hand somewhere between two frames. So we never point at one “release frame”. We mark release where it can be seen, say so where it can’t, and say how often the wrist was found.

Where the hand comes over, delivery after delivery

The long end-on clips can’t show the action in detail, but they show something a single side-on clip can’t: the same bowler, ball after ball, from the same camera. For every live delivery we took the frame where the bowling wrist was highest and marked the wrist, relative to the bowler’s own body.

One body outline seen from behind, leaning to its left at release. Above the head, Bumrah's green dots form a tight, round cluster almost on top of his head; to the right of it, Wood's black dots form a taller, narrower cluster further out over the bowling shoulder. A ring round each cluster marks where most deliveries fall. — Seen from behind the bowler, so left in the picture is the bowler's left. One dot per delivery, placed relative to each bowler's own hips and scaled by his own torso length, so camera zoom drops out and both share one outline (a typical release position, not either bowler's exact pose). Each ring holds most of that bowler's deliveries. Some of that spread is the frame rate: at 25 frames a second the highest-wrist frame can be a frame before the ball leaves the hand. A flat 2D picture from one broadcast camera, not a release height, and the deliveries were found automatically, not checked by a coach. Footage: ECB official highlights (Bumrah, England v India; Wood, England v Australia).

What a coach would look for in a picture like this isn’t where the dots sit but how tightly they gather. A bowler whose hand arrives in the same place ball after ball has a repeatable action.

Where the ball landed

The two long clips are end-on match highlights, filmed from behind the bowler. They show where each delivery pitched, roughly. For each live delivery our software marked a landing zone from the broadcast picture, the way a coach would tag it at the nets: full, good or short, and off, middle or leg relative to the batter.

Bumrah

Bumrah: 48 of 68 good length on off; 8 of 68 good length on middle; every other zone too few to show.

68 deliveries · Full 6 · Good 58 · Short 4

Off 53 · Middle 12 · Leg 3

Wood

Wood: 15 of 24 good length on off; 5 of 24 good length on middle; every other zone too few to show.

24 deliveries · Full 1 · Good 20 · Short 3

Off 17 · Middle 7 · Leg 0

Marked by our software from the broadcast picture: not ball tracking, and not coach-tagged. Live deliveries only; replays dropped. Bumrah: 68 of 71 live deliveries showed where the ball landed; Wood: 24 of 24. Stumps at the top, off side on the left for every batter. A cell with fewer than five deliveries reads "too few". Footage: ECB official highlights (Bumrah, England v India; Wood, England v Australia).

Both bowlers lived on a good length on off, the channel that makes a batter play and miss or edge. That’s the Test-match plan, and the grids show it in a way any club player understands. The length calls are the least certain part: at broadcast resolution the ball is a few pixels across when it lands.

What a camera can’t tell you

Bumrah’s bowling arm is often described as hyperextending: at the top of the action the elbow seems to bend slightly backwards past straight. Replays of it get argued about every summer.

This is exactly where one camera stops being useful. An elbow isn’t a hinge sitting flat to the lens. The upper arm rotates, the forearm naturally angles away from it, and the whole arm swings through three dimensions in a fraction of a second. Film the same arm from a different angle and its bend on screen changes, even when the elbow hasn’t moved at all.

A simulated bowler, a grey clay figure, not footage of any player. The arm is frozen just before release with a fixed elbow while one camera circles once. The green line is the arm as this camera sees it: from one position the elbow looks bent, from another nearly straight, yet the arm never moves. Eight seconds, no sound.

That’s why the ICC tests a suspect action in an accredited laboratory, with markers on the arm and many cameras around the bowler, not from match footage.

So BatSwing never calls an action legal or illegal, never flags hyperextension and never gives an elbow angle. If you’re worried about a bowler’s action, the route is a qualified coach and, if needed, a proper laboratory assessment.

What a coach would take from this

Read the moments, not the numbersFront-foot contact and release are the two frames to look at first. A side-on phone sees them without a single angle.
Same thing, ball after ballBraced, softening or bending: no front leg is "right". What matters is whether a bowler repeats it, and whether it changes when they tire.
Know what a camera can't tell youOne camera can't judge an elbow. Legality is a laboratory question, never a phone's.

What this means at an academy

None of this needs a broadcast camera. One phone on a tripod, side-on from the bowling-arm side, sees the moments, the front leg, the head and the follow-through. A second phone behind the bowler sees where the ball lands.

We’re building that for academy nets sessions: the key moments proposed for the coach to confirm, the front leg read in words, coach-tagged landing zones, and a recorded count of balls bowled. It isn’t in the product yet. Until it is, the breakdown above is the vocabulary; the coach is still the one who calls it.

Sources

End-on footage: ECB official highlights (Jasprit Bumrah, England v India; Mark Wood, England v Australia). Side-on footage: broadcast replays of Australia v India matches (Bumrah in a Test; Mitchell Starc in a white-ball match). Front-on footage: social clips of nets sessions (Jofra Archer; Dale Steyn, published by Free Life Official). Short derived stills and one short excerpt, hosted by BatSwing for technical commentary; all rights remain with the rights holders.
ICC regulations for the review of bowlers reported with suspected illegal bowling actions: icc-cricket.com.
Felton and King (2016), the effect of elbow hyperextension on ball speed in fast bowling: Loughborough University repository.
Front-foot contact in fast bowling, Felton et al.: Nottingham Trent repository.

This is an independent technical analysis produced by BatSwing for editorial and commentary purposes. It is not an official assessment, endorsement or ranking, and is not affiliated with or endorsed by the players, their management, any board, any team or any broadcaster. Skeletons, traces and strips are derived illustrations made from short excerpts of publicly broadcast footage for critical commentary; all rights remain with the rights holders. Takedown requests can be sent to [CONTACT EMAIL] and are actioned within 24 hours.