It really depends on what your agenda is. Ie, regarding Napoleon, the majority of people over here (Serbia) will remember that he had his ass handed to him by the Russian winter. Why? Because people over here like the Russians and enjoy the narrative that they stopped both Napoleon and Hitler.
I am really not sure where the entire idea that late failures are remembered more comes from. We all decline over time. The time of the decline depends on the profession, but it does come, for players as well as managers.
There will be no late failures to remember Zidane for if he decides to never manage again, but everyone who has been in the game for a while have had failures. Pep has not won the CL without Messi and that freak midfield. SAF has won it only twice. Klopp has lost how many finals, six? And so on and so on.
Let's go back to Zidane. Would you say that he, as a player, is mostly remembered for the Materazzi headbutt? For anyone who was around in 1998 and 2001, the answer is no.
To go back to the Napoleon thingy... What people will remember Mourinho by depends on how they feel about him. The neutrals will probably see him as the best manager of the 00's, who declined in the following decade. But it's hardly a stick to beat with him with, not that many manager to remain at the very top for a decade plus.
