Now you are askng another question. The point is that MAE is used to see how much one trade had been dragged down before it was closed to answer your original query.
so are you saying this MAE only available when connected to myfxbook? and mt4 does not have this information?
Metaquotes publishes end of day statement that has timestamp, order id, price, equity, which you can find under the history tab. From this information available on the statements, you can write a program to plot daily end-of-day metrics like equity chart, drawdown, MAE, profit factor etc even if the trader has shutdown his or her machine as these statements are generated from live servers and all regulated brokers keep such records as long as the account is active. Yes some bucket shop brokers delete old statements as it takes valuable storage space.
It is up to the good analytical program to extract these data to plot it accurately. Myfxbook does a very good job too like others out there.
When a trader keeps the account connected with myfxbook, then it is possible to collect high resolution intraday data and record any sudden spikes in data which otherwise could not be captured by end of day statement.