I used the word 'lethal' for a reason. Diego Costa (a bit like Drogba) always pops up with a goal when you need him to.
I would take Costa over Morata (and Lukaku in case someone thinks i'm being biased) because he does more for the team and scores important goals.
Costa has been instrumental in two title winning teams with classical counter attacking managers. He is a premium no.9. Far above the level of Morata.
I'm not sad that Morata missed all his chances. I just think these blips in form are temporary. The kid will rebound, as will Lukaku. Both quality players.