For every team that won, theres a team that lost, and therefore all this stat proves is the distribution of win/loss ratios on XBL is larger than on PSN.
The best players might have a higher ratio than the best players on PSN, but it also means the worst have a worse ratio on XBL than PSN.
Comparing those ratios directly is as silly as comparing champions league football clubs based on their domestic league win ratios, since some leagues are far more competitive than others and its not unusual for even the worst teams to perform well and beat a top team. Ofcouse when it comes to champions league where they actually play each other, the 'top' clubs from leagues which are not very competitive, generally do not perform as well as the clubs from leagues which are competitive.
Unless all PSN and XBL players get thrown onto the same servers, it cant be proven.







