I genuinely don't think Aguero saw City as a step down though. They (at the very least) looked better placed to win trophies in the next few years than Atletico. Whereas, frankly, Di Maria did see us as a step down.
And yeah, they come across as completely different characters too. Whether or not Aguero "gave a feck about City", he sure gave a feck about getting himself a few of the trophies within reach. Arguably, Di Maria doesn't even have that worry, with what he's won.
I'd say Toure's move is more comparable to Di Maria's, and for all his supposed character faults, you can't question his commitment to the cause once he joined City. He looked as fired up for it as anyone.
I don't know.. maybe a few warmer months, and a break will do Di Maria some good.