MEW is a wallet that once your eth/tokens were transferred, you can only trace the transaction hash. When it was transferred and to what address, though you can report it to MEW by adding its address to watch list but you cannot track how the person got your key, either brute force, phising and etc.
Yes, we just can report it to MEW by adding its address to the watchlist. But some keyloggers are used to easily connect to the main account of the wallet,
And this can also be prevented if if the computer / laptop / the like will die every time you are not used so that your IP connection will not be detected by the hacker.