1) Lack of quality up front
Arsenal have needed a top class striker for some time and despite having failed in attempts to bring Luis Suarez in a couple of seasons ago they still only have two forwards; Olivier Giroud and Danny Welbeck, neither of whom are top quality. The lack of a world class, or even very good forward, limits Arsenal in tighter games, whereby they need someone to steal a winner, or lead the line under tough conditions. Arsenal won’t finish the season with 20 goals from either Giroud or Welbeck so will rely on Alexis Sanchez to pick up the burden, whether he can do so over 38 games remains to be seen and even if he can that might not be enough goals.
2) Defensive organization
The club signed Petr Cech and a huge fuss was made about how now Arsenal have the quality to keep clean sheets and win the league. In reality this was misleading and papered over a lot of huge tactical cracks that there are at Arsenal. The club cannot defend set-pieces and at times look like they are very open in defence. Much of this is down to the way the manager has organized the side. Otherwise why would Arsenal be so consistently bad at defending from corners and free-kicks? It doesn’t matter who is in goal, Arsenal have conceded a lot of goals this season, even at this early stage. A few clean sheets against United, Watford and Bayern do not disguise this.
3) Thin squad
Arsenal’s only summer signing was Petr Cech leaving the squad to be quite thin. Arsenal missed out on some targets but to bring in just one new signing to strengthen a side that was way off the top last season is foolish and naive. Arsenal do not have a lot of depth and with players prone to injuries this could cost them the title. Manchester United and Man City have bigger squads and can handle the most severe injury crises. Arsenal on the other hand are only ever a couple of injuries away from having their season come off the rails.
Arsenal’s victory over Bayern might make people think that they are ultimately winners but a group stage game is never that high pressure. When it really matters over the last ten years or more we’ve seen Arsenal come up short. Even their 2-0 loss at Chelsea now looks quite embarrassing given Chelsea’s terrible form. In the big games, under big pressure, they simply don’t have the mentality to come up with the goods. Over the course of a full season you’d expect sides who have been there and done that and who have managers who have done it (more recently than Wenger’s whose record over the last 11 years is poor) to come out on top. Arsenal’s chances of winning the title depend on a total melt down of other clubs such as City and United.