Open-Play xG vs Set-Piece xG: Why the Split Matters

The open-play versus set-piece xG split divides a team's expected goals by how each chance began. Open-play xG comes from chances created in the run of play, while set-piece xG comes from dead-ball situations: corners, free kicks, and penalties. Separating the two reveals how a side generates danger, not just how much, reshaping how analysts read attack and defence.

What counts as set-piece xG

A set-piece is any restart of play from a stationary ball after a stoppage. In xG terms, set-piece chances are the shots that flow from those dead-ball situations rather than from continuous open play. Most models tag the origin of every shot, so the same total expected goals can be sliced cleanly into an open-play column and a set-piece column.

Three sources make up the set-piece bucket:

• Corners. The first contact, the second-phase scramble, and any shot that the routine produces all count as set-piece xG. Because corners convert at a low base rate, each one usually contributes only a small fraction of expected goals, but they accumulate across a season.
• Free kicks. Both direct attempts at goal and indirect deliveries swung into the box belong here. A whipped free kick from wide is, in xG terms, closer to a corner than to a direct shot at goal, and good models treat the two differently.
• Penalties. Every penalty is a set-piece chance, and a very valuable one.

Penalties are the reason the split needs a third layer. A penalty is worth roughly 0.76 xG every time, regardless of who takes it or which match it falls in, because the model is judging a near-fixed situation rather than the player. That makes penalties a blunt instrument inside any aggregate. A single awarded penalty adds about three-quarters of an expected goal to a team's total in one stroke, which can swamp twenty minutes of patient open-play work. For that reason, analysts routinely pull penalties out entirely and report non-penalty xG (npxG), leaving a number driven by chances a team actually constructed.

Why the split matters in attack

Two teams can finish a season with identical xG totals and have built them in completely different ways. One side might generate almost everything through open-play passing moves; the other might lean heavily on corners and free kicks to reach the same figure. On the table they look alike. In reality they are different teams with different risks.

A high set-piece share tends to signal a more volatile attacking profile. Set-piece conversion swings hard over short samples because the underlying events are rare and the base rate is low, so a team that depends on dead balls for a large slice of its goals can run hot for a month and cold for the next without anything fundamental changing. Open-play xG, generated shot after shot across many possessions, is smoother and tends to track actual goals more closely over time.

The flip side is that set-piece output is more coachable. A team cannot easily manufacture twenty extra open-play chances a season by decree, but it can rehearse corner routines, drill delivery, and target a specific zone until the first-contact rate climbs. Set-piece xG is, in that sense, the part of attack most responsive to deliberate training-ground work. A rising set-piece share is sometimes a sign of a side that has decided to professionalise an area rivals have neglected.

Why the split matters in defence

The defensive side of the split is where it earns its keep. xG conceded can be divided the same way, and conceding a large amount of set-piece xG points to problems that are specific and, crucially, fixable. A defence that limits opponents in open play but leaks chances from corners and free kicks usually has a marking issue rather than a structural one.

The conceded set-piece column tends to expose a short list of recurring faults:

• Zonal weaknesses — gaps between zones, or a zone left undermanned, that deliveries are repeatedly aimed at.
• Man-marking mismatches — a smaller defender consistently picking up a dominant aerial target.
• Aerial frailty — a side simply losing too many first contacts in its own box.
• Second-phase disorganisation — bodies in the right places for the initial delivery but scrambling once the ball drops loose.

Each of those is addressable on the training ground in a way that a leaky open-play defence, which often reflects deeper issues of shape, pressing, and personnel, is not. A back line bleeding open-play xG may need a new system; a back line bleeding only set-piece xG may need a fortnight of repetition. Reading the two columns separately tells a coach which problem they actually have.

Dead balls as a market inefficiency

Managers and dedicated set-piece coaches have increasingly treated dead balls as undervalued territory. The logic is straightforward: if most teams once prepared corners and free kicks loosely, then small, cheap improvements in delivery, movement, and defensive organisation compound into a real goal difference at no transfer cost. The gap between the best and worst set-piece sides in a league can be worth several goals a season in each direction, and in tight races that is the margin between finishing positions.

That is why the split has moved from a curiosity to a planning tool. Platforms such as RubiScore separate open-play and set-piece xG so that a team's profile is legible at a glance, rather than buried inside a single combined figure. A club that knows precisely how much of its expected-goals output is dead-ball driven can decide whether that dependence is a strength it has engineered or a vulnerability it has stumbled into.

Why stripping penalties gives a fairer comparison

When the aim is to compare attacks fairly, penalties distort more than any other category. They arrive semi-randomly, they are worth a large fixed chunk of xG, and they say little about how well a team builds chances. A side that has been awarded several penalties can look like an xG overperformer when its open-play creation is ordinary, and a side starved of penalties can look worse than it is.

Non-penalty xG removes that noise. By stripping the roughly 0.76 xG that each spot kick contributes, npxG isolates the chances a team generated through its own construction, whether in open play or from worked set-piece routines. For ranking attacks, projecting future output, or comparing one season to another, npxG is the cleaner number, and it is why the metric now sits beside raw xG on most serious data displays.

What a high set-piece share tells you about sustainability

The split is at its most useful as a forward-looking sustainability check. When a team is scoring freely, the first question worth asking is where the goals came from. A side outscoring its xG largely on the back of converted set-pieces is on shakier ground than one doing the same through open-play volume, because set-piece conversion regresses harder and faster.

A few signals are worth weighing before assuming an attacking run will hold up. A large share of goals from penalties is the least sustainable, since penalty awards are difficult to repeat on demand. A heavy reliance on corner conversion is the next most fragile, given how low the base rate sits. A high but stable set-piece xG built on a strong first-contact rate is more durable, because the underlying process — getting good heads to good deliveries — is repeatable even when the goals briefly dry up. And a side whose scoring is anchored in healthy open-play npxG is the safest bet to keep producing across the fixtures ahead. Read this way, the split stops being a description of the past and becomes a quiet forecast.

Holding open-play and set-piece xG apart turns a single total into a story about method, risk, and what a team can realistically expect next. The two columns, split out for competitions worldwide, are published on rubiscore.com, where the way a chance began sits alongside the chance itself.