Every case where a nation brought back the same generation — the modal four-year birth window of the squad was the identical actual window one World Cup later — instead of refreshing it. Ranked by the collapse in over/under from t to t+4. Cache-only, freeze-respecting.
The type specimen: Australia held its golden generation (born 1978–1981) from 2006 to 2010 rather than refresh it — mean age rose +0.5, and a squad that over-performed by +0.31 in 2006 under-performed by -0.22 in 2010.
| Nation | Cycle | Window | Δage | Δapps/pl | OU t | OU t+4 | Δ |
|---|---|---|---|---|---|---|---|
| 🇩🇪 Germany | 2014→2018 | 1987–1990 | +0.9 | +26 | +0.26 | -0.76 | -1.02 |
| 🇪🇸 Spain | 2010→2014 | 1985–1988 | +2.0 | +68 | +0.14 | -0.72 | -0.86 |
| 🇦🇺 Australia | 2006→2010 | 1978–1981 | +0.5 | +4 | +0.31 | -0.22 | -0.53 |
| 🇺🇾 Uruguay | 2010→2014 | 1984–1987 | +1.5 | +57 | +0.55 | +0.09 | -0.45 |
| 🇧🇷 Brazil | 2002→2006 | 1973–1976 | +2.0 | +65 | +0.47 | +0.03 | -0.44 |
| 🇦🇷 Argentina | 2014→2018 | 1985–1988 | +0.7 | -0 | +0.29 | -0.14 | -0.43 |
| 🏴 England | 2006→2010 | 1978–1981 | +3.1 | +80 | +0.13 | -0.26 | -0.39 |
| 🇲🇦 Morocco | 2022→2026 | 1996–1999 | +0.3 | +12 | +0.78 | +0.41 | -0.38 |
| 🏴 England | 2002→2006 | 1978–1981 | -1.4 | +11 | +0.34 | +0.13 | -0.21 |
| 🇮🇷 Iran | 2022→2026 | 1992–1995 | +1.5 | +2 | -0.24 | -0.41 | -0.16 |
| 🇷🇸 Serbia | 2018→2022 | 1994–1997 | +0.1 | +32 | -0.16 | -0.32 | -0.16 |
| 🇦🇷 Argentina | 2006→2010 | 1978–1981 | +1.0 | -2 | +0.29 | +0.16 | -0.13 |
| 🇧🇷 Brazil | 2014→2018 | 1985–1988 | +0.2 | +18 | -0.02 | -0.07 | -0.05 |
| 🇨🇮 Ivory Coast | 2006→2010 | 1980–1983 | +1.2 | +22 | -0.13 | -0.15 | -0.03 |
| 🇲🇽 Mexico | 2014→2018 | 1988–1991 | +2.0 | +33 | +0.21 | +0.19 | -0.02 |
| 🇨🇭 Switzerland | 2014→2018 | 1989–1992 | +1.2 | +21 | +0.11 | +0.13 | +0.02 |
| 🇺🇾 Uruguay | 2014→2018 | 1984–1987 | -0.5 | -3 | +0.09 | +0.14 | +0.04 |
| 🇧🇷 Brazil | 2022→2026 | 1991–1994 | +1.4 | +20 | -0.07 | +0.02 | +0.08 |
| 🇨🇭 Switzerland | 2022→2026 | 1995–1998 | +1.3 | +27 | +0.19 | +0.28 | +0.09 |
| 🇨🇲 Cameroon | 2010→2014 | 1983–1986 | +1.0 | +23 | -0.16 | -0.04 | +0.12 |
| 🇨🇷 Costa Rica | 2002→2006 | 1974–1977 | +0.3 | +6 | -0.29 | -0.15 | +0.14 |
| 🇶🇦 Qatar | 2022→2026 | 1990–1993 | +2.5 | +2 | -0.21 | -0.04 | +0.17 |
| 🇩🇪 Germany | 2022→2026 | 1993–1996 | +1.2 | +13 | -0.53 | -0.27 | +0.26 |
| 🇬🇭 Ghana | 2022→2026 | 1997–2000 | +2.2 | +2 | -0.01 | +0.31 | +0.32 |
| 🇲🇽 Mexico | 2022→2026 | 1995–1998 | -0.7 | -12 | -0.27 | +0.14 | +0.41 |
| 🇭🇷 Croatia | 2014→2018 | 1986–1989 | +0.5 | +52 | -0.31 | +0.57 | +0.88 |
Window conversion (DESIGN v3 wasted-generations leaderboard) is a distinct peak-quality-vs-peak-result analysis — deferred to its own item, not folded in here.