Despite all the (entirely justified) concerns about how many we're conceding, we have actually conceded 1 goal less over the first 15 games of this season compared to last.
Last season it was 20, and this season its 19. Last season 9 teams conceded fewer in first 15 games (and 10 had conceded more). This season only 8 teams have done better up to now (though only 8 have done worse).
Correspondingly, we have actually scored 4 fewer goals in first 15 games.
Last season, we were leading the league in goals scored at this stage with 37 (Arsenal 36, Chelsea 33 and Man City 32 being the only others to be averaging more than 2 per game).
This season we're only third best with 33 (exactly same as last season's third best, Chelsea). Man U are second with 35 (so slightly worse than Arsenal last season). Man C are an outlier with 44 goals before even playing their 15th game (they're theoretically on track for 119 or 120 over 38 games).
However, re away games only, both last season and this, we played 8 away games in our first 15 games. Last season we scored 16 and conceded 14. This season its 20 and 17.
So the perception that our defence is shakier, but our attack more potent, might be an accurate one if we confine the analysis just to away games. However, overall, in the league, the stats don't quite bear it out.
For what it's worth (very little, of course) in 2013/14, after 15 games, we had scored 1 more goal than this. (Man C had 41 goals after 15 games, and we were next highest). We had conceded 1 fewer goal in 13/14 than we have this (and were joint 7th "best" for this stat).