Soccernet have a great story up, where they look at Diego Maradona's troubled tenure as Argentina coach. I can't help thinking that the best coaches – Mourinho, Ferguson, Van Gaal, Hiddink, Benitez, Wenger – weren't great players... and despite a few notable exceptions (Cruijff, Beckenbauer), the greatest players don't necessarily make great coaches.
It's a lesson few sports teams seem able to learn.