Low xG could prove to be a concern. There are many mitigating factors, though, who prevent us from drawing safe conclusions at the moment. We are, indeed, at the end of a very non-friendly fixture list. Furthermore, we screwed up the tactics in our two opening games of the season, which resulted in serious adjustments regarding personnel and player roles. Also, don't forget that we have a new manager in a new league, trying to pick up the broken pieces the previous regimes left behind.
Comparing a game between two top-six rivals with any other game can also lead to false conclusions. When Chelsea are playing Leicester, Villa or WHU at the Bridge, they'll try to force the issue because anything other than the three points is a failure. They'll take the initiative and they'll push their lines higher. It will usually be a game in which, unlike in the big matches, the roles of both opponents will be clearly defined. The Spurs game falls under the same category because of Conte's nature as a manager.
Last, but not least, the forward issue should not be underestimated. All this time, we've been trying to cope without our forward of choice. Martial's role on the pitch is of the utmost importance. There are enough goals between Rashford, Antony and Bruno to get us through the season. But when you have two wide men whose best quality is cutting inside and finishing, and (false) #10 who thrives on arriving late in the box, you need the player who will be able to operate between the lines. Plus, it's a known fact that ETH has done wonders with Tadic in the role of this drifting forward. And the 4231, with the #10 and the #9 interchanging positions, would suit Bruno's often frantic/erratic movement better.
Of course, this doesn't mean that everything will be OK over time. Time alone helps you to work and discover your limits. It doesn't take those limits away. Toward the end of LvG's first season at the club, we went to SB to face Mou's Chelsea and, for the vast majority of the game, we had them pinned down in their own box. We lost that game 1-0, as we could have lost this one. Our problem was that we couldn't make the most of the lion's share of possession we enjoyed. I'm not drawing parallels between then and now. I have tremendous faith in ETH and a very good feeling about the man. It's just a reminder that "dominating" the possession stats is only half of the job required to be done. Otherwise, the likes of Mourinho and Benitez wouldn't have fallen so far behind.
Anyway, we are at a good place. We are looking like a team that's going places. After the nightmare of last season, this alone constitutes a minor miracle. It's so nice to watch United and expect good things on the pitch from our players. Sit back, enjoy the ride and let's see where the end of the season will find us.