He'll stabilise them a bit, but I don't expect miracles from them next year. If he's given the time (and I expect he will as the board there is a meek bunch) then within two seasons I can see them getting back in the top four and maybe going from there. There will be plenty of ups and downs though, its just whether the fans could be patient with it.
I liken Arsenal to painting a garden fence ,when you put the first coat on you feel like its never going to be enough so you wait patiently for it to dry ,then after the second coat you foolishly think maybe it doesn't need a third.
I mean essentially its the same paint but you convince yourself that it will eventually dry to resemble the colour you expected when you bought the thing and that's when reality finally bites ,you're so obsessed with reaching the requisite shade that you have been painting this fence for a fucking fortnight and you've forgotten the disinterest you first shown when the wife suggested you paint it.
I mean ,you could simply just replace the paint but the desperation to prove patience is a virtue and persistence will prevail has become all consuming and in all this madness you fail to notice the wife has poured turps into your paint tub and replaced your brush with wire wool and in a moment of quiet contemplation you think 'Ive done more harm than good' and the 'world and his wife' and their incessant protestations were right all along and all youve achieved is the loss of elasticity in your sack due to your gonads hanging out of those shorts you thought would be cool to paint in.