From an ESPN article:
To answer this question, we enlisted the help of ESPN's Soccer Power Index (SPI), an algorithm designed to forecast soccer results. Debates on Europe's top league usually devolve into arguments over which country has the strongest overall team -- comparing Spain's Barcelona and Real Madrid with England's Manchester clubs, for example. But the true test of a league's strength is not at the top of the table but in its quality at the middle and bottom. So SPI grouped the top five, middle five and bottom five squads from England's Premier League, Spain's La Liga, Italy's Serie A and Germany's Bundesliga to create three fictitious 20-team leagues. SPI then simulated each of these leagues 10,000 times. In the top group, Barcelona and Real Madrid -- arguably the two best teams in the world -- predictably won a combined 91.2 percent of simulations. Meanwhile, although Liverpool dominated the middle league, La Liga sides Sevilla, Athletic Bilbao and Mallorca all averaged a top-five finish. Similarly, in the bottom group, the Premier League's Aston Villa won most often, but Villarreal, Granada and Real Zaragoza were all among the best five. Overall, La Liga teams had an average finish of 8.8 across the three leagues, compared with the EPL's 9.9. (Serie A finished at 11.26 and the Bundesliga last at 12.10.) -- Albert Larcada
