Morata has everything a striker needs except confidence in front of the goal. He's clearly overthinking, but his strength, positioning and movement are excellent. I'm not surprised his xG is so high.
Lacazette on the other hand is slow, poor movement so he never receives the ball, positioning is poor so defenders always have a run on him, but his shooting is great.
IMO jury is not out, Lacazette is just irredeemably shit and could be a Chicarito at best, Morata could be 20-30 goals a season.