Maybe the English researchers are biased because the three most successful English soccer teams in recent memory (Liverpool, Manchester United, and Arsenal) are biased in their conclusion. Let's take a look at American sports:
None of the winningest teams in each of the three major pro sports (Celtics in the NBA, Cowboys in the NFL, and Yankees in baseball) wear red. Ditto for the two winningest college football programs (Michigan and Notre Dame, both of which have slightly less successful arch-rivals [Ohio State and USC] who wear red) and three winningest college basketball programs (UCLA, North Carolina, and Kentucky.) In contrast, the archetypes for losing in the NFL (Arizona/St. Louis/Chicago Cardinals) and the NBA (San Diego/L.A. Clippers) both wear red uniforms.
And no, my Michigan bias has nothing to do with this conclusion.