Our lack in certain areas of the squad is obvious and has been for some time. In my opinion a degree of blame must be positioned outside Arsene's door, he has had the opportunities to strengthen and he has not done so. To keep this in context there has definitely been some progress from last season, however this could have been considerably greater if the right purchases had been made at the right time, obviously this is much easier to say 'Championship Manager' style than to do in practice, nonetheless there is now no doubt in the majority of Gooners' minds that some significant changes must be made to the squad this summer by the manager.
Stasis and maintaining the status quo will result in the same failings next season if nothing is done. The fact that Arsene openly admitted that we lack 'maturity' against Spurs is a sad indictment on his own decision not to buy some solid experienced players for the squad over the past couple of seasons. He is now pointing out our clear lack of defensive strength in depth, another thing that has been blatant for some time.
Take out first team squad and analyse it. Realistically you need one top keeper, one solid deputy and a decent third choice, two full backs for each side, arguably four quality centre backs, two decent defensive midfielders, four other all roundish midfielders, four decent wide players and four strikers. This analysis takes a bit of guessing and a few assumptions. I shall assume that the only youngsters ready for contention are Wilshere/Wojciech Szczęsny and I will assume that Gallas/Silvestre/Campbell are off.
Goalkeepers. We need a top notch stopper, Almunia has not been good enough. Wojciech Szczęsny may be good enough in the long term but if not ready yet then we need to invest in an experienced stopper.
Fullbacks. Here we are ok. Sagna/Eboue at right back and the latter may well be about to displace the former given their recent form. Gibbs/Clichy is enough at left back.
Centre backs. Here we are woefully short. Vermaelen is on the team sheet but we need a top notch commanding partner for him. If Djourou gets fit then he can be a decent squad player, Campbell can stay on for a year maybe, but we still need one more, whether Bartley is up to the Premiership will be key, if not then we need two centre backs for sure.
Defensive midfield. We are very weak here, Song is our only midfielder who can defend, we need at least one more player who can play this role, I would also argue that we need to replace one or two of our technical ball players with more physical and robust all round combative midfielders. The balance of the squad is way off, we need more Parlour type players. JET, Lansbury, et al should not be forgotten as well but they are arguably more attacking players.
Midfield. We have enough technical ball players, of this there is no doubt. We have Cesc, Diaby, Denilson, Rosicky, Nasri, Merida and Ramsey.
Wide forwards/Wingers. We have plenty of attacking midfielders but not many are genuine wide men, maybe this isn't neccessary given the 4-3-3 system. I would count Arshavin, Walcott, Wilshere as these players, obviously the likes of Merida, Nasri and Rosicky give us a flexibility in this department.
Strikers. We have RVP/Bendtner/Eduardo. Eduardo is running out of time to prove himself, as is Vela. It looks like at least one of these two will leave in the summer, Chamakh appears a done deal.
Overall it seems obvious that we need to strengthen ourselves up defensively. We do not need any more young players either. Arsene needs to go out and buy an experienced goalkeeper, at least one experienced centre back and a defensive midfielder. This is a minimum. We need more defensive strength in the first team and on the bench, there is also an argument that we need to sort out the way that our defense is coached to cut out the basic errors we have been making far too frequently of late. It is the manager's job to address these problems with our squad and if he does not then he should take the blame, sometimes enough is enough.