Once you have Winning Eleven 49 installed, the customization doesn't stop. The community has created "sub-mods" to enhance the experience:

After installation, go to "Settings.exe" and turn off "Frame Rate smoothing." WE49 runs best at a locked 60 FPS.

No one could select them in normal play. But modders soon discovered that if you lost 10 consecutive matches in Master League on the highest difficulty, The Eleven would appear as a secret opponent in a friendly match. No announcement. No fanfare.