As always, we tend to over-react on a defeat and conclude the squad is in crisis.
To me, the biggest issue is motivation - not tactics. Lazio played as if it was the game of their lives. We came out of the blocks guns blazing but then nose dived after the first 10 min until 20m before the end of the game. Dybala put it best when he said that they lacked "desire".
Also bear in mind, despite our players putting in such a sub par performance we were effectively playing in Lazio's home stadium - if this was a 2 legged tie, this would have been a good result.
Yes there are things to be worried about, but lets not get totally carried away. The whole team was basically losing every 1 on 1 battle for over 60min in this game - Lazio were just quicker to every ball. That is either a reflection of 1) Desire; or 2) Lazio's physical preparation is more advanced for whatever reason.