Each side’s expected goals for a matchup are computed as:

λ_home = (Attack_home × Defense_away ÷ League Avg xG90) × Home Advantage
λ_away = (Attack_away × Defense_home ÷ League Avg xG90) × Away Factor

League Avg xG90 is set to 1.48 (the blended MLS/Liga MX combined-season average). Home advantage is a 1.12× multiplier on the host club’s expected goals and a 0.94× discount on the traveling club’s; both are set to 1.0 for neutral-site games. Final scoreline probabilities come from independent Poisson distributions over λ_home/λ_away (0–6 goals), with the “no draws” shootout modeled as a 50/50 coin flip applied to the regulation-draw probability mass.

League factor

Before any of the above, every club’s raw base xG90/xGA90 gets a league-strength adjustment applied separately to attack and defense: Liga MX xGF ×1.035 (+3.5%) and xGA ×0.965 (−3.5%); MLS xGF ×0.985 (−1.5%) and xGA ×1.015 (+1.5%). Each league’s two halves are sized so they sum to the intended combined swing — a 7% swing for Liga MX, 3% for MLS — reflecting the view that Liga MX clubs, drawn from a deeper/older league with heavier continental hardware, tend to outperform what same-league-only xG comparisons suggest against MLS opposition, and vice versa. Change LEAGUE_XGF_FACTOR / LEAGUE_XGA_FACTOR in the source to test other assumptions.

Squad-value factor

On top of the league factor, each club gets a second multiplier based on where its Transfermarkt-implied squad value ranks against all 35 other clubs in the field (not just its own league) — from 0.92× at the bottom of the pool to 1.08× at the top, linear by rank, applied to attack (multiply) and defense (divide) the same way as the league factor. The idea: a club that’s dramatically outspent its group, or is being dramatically outspent, probably over/underperforms its raw xG sample by a bit — spend is an imperfect but real signal of squad depth and quality that a partial-season xG number doesn’t fully capture. The Power Ratings table above shows both multipliers (Lg×, Val×) alongside the raw and adjusted numbers so you can see exactly what each one did.

Why Liga MX’s base rating is now full-season xG, not a squad-value proxy

MLS’s 2026 season is deep enough (17–19 games per club through Aug 2) that season-long xG/xGA is a reliable signal on its own. Liga MX’s Clausura 2026 is only 2–3 games old as of kickoff, so raw early-season xG alone is extremely noisy — a club like Necaxa (2.44 xG/90 through 2 games) is not sustainably one of the best attacks in the region. Earlier versions of this model corrected for that with a squad-value-implied prior. That’s now been replaced with something better: a real, complete 18-team xG/90 table for the combined 2025-26 season (Apertura 2025 + Clausura 2026, 34–44 games per club depending on Liguilla run) via FootyStats. Each club’s base rating is 75% that full-season number, 25% its early Clausura 2026 form — real data on both sides of the blend, weighted toward the far larger sample. As the current Clausura sample grows, that weighting should shift further toward live 2026 form.

Liga MX base xG90 = 0.25 × (early Clausura 2026 xG90) + 0.75 × (FootyStats 2025-26 combined xG90)
Liga MX base xGA90 = 0.25 × (early Clausura 2026 xGA90) + 0.75 × (FootyStats 2025-26 combined xGA90)

One proxy remains: Atlante FC has no Liga MX playing history of its own yet, having acquired Mazatlán FC’s registration for 2026-27. Atlante’s full-season anchor uses Mazatlán’s actual 2025-26 xG/90 (1.16 / 1.88) as the closest available stand-in.