He was 17 when Liverpool lost 7-3 to Ajax in the European Cup and Shankly famously quipped "when you lose the ball, continental teams don't give it back."
Liverpool changed their tactics the next year to value possession and patient build up.
Wenger didn't unlearn the lesson when Mourinho won the Champions League with Porto in 2004 and again with Inter in 2010 playing a reactive style that is easier on the legs over a long season of playing twice per week and that can provide more space for creative players to do creative things.
Wenger was 55 when Porto won the Champions League. But that was the same season Arsenal went undefeated in the Premier League. That is why this entire saga is so fascinating. Unlike Shankly, who had a humiliating defeat to realize he needed to change his ways, Wenger had a brilliant success at the moment when he could have noticed a significant tactical event.
That 2010 Inter-Barcelona semi-final is etched into my brain. That Barcelona team was wonderful and held 71 percent of possession and lost the game. Wenger was 61 at the time of that game and there is no purer example of the team Wenger wanted to be (Barcelona) failing. That Wenger didn't learn to be more flexible after that is something a reporter should really ask him.