I like xG. I think it's a good metric. It also has some good predictive qualities if you take some history (assuming you can derive some sort of history for a player).
Morata is all over the place:
14/15 - Juventus - 8G - 5.01 xG
15/16 - Juventus - 7G - 8.10 xG
16/17 - Madrid - 15G - 9.52 xG
17/18 Chelsea - 11G - 13.90 xG
So, that's 41G vs 36.53 xG in 4 seasons.
https://understat.com/player/1804
Either he's regressing to the mean (statistically) from that super efficient 16/17 season (bad news for us). Or, he's a good finisher who will outperform (slightly) his xG (his xG should go up under Sarri, if you're curious, Mertens and Higuain both had xG numbers between 20-25 under Sarri). These 4 seasons don't tell us very much for Morata (in comparison, Aguero has outperformed his xG in 3 of the last 4 seasons)
In relation to the match today, it really shows how flattering the scoreline was (it's early days, it's to be expected, before anyone accuses me of not being patient).