To be honest I am fascinated to see how he spends 100-160m (depending on sales) without coming up with at least a few stinkers.
Someone mentioned that they could well be shopping in the 15m + bracket which is risky (see: Osvaldo, Dani)
Even if they are you are looking at 6-8 new players. I am struggling to think of "legitimate" 30m players (so not over inflated prices) who would actually go their after they have finished in 11th and have many teams to try and overtake.
6-8 players is some upheaval and there is no guarantees Koeman will repeat the trick of managing it. At Southampton I am sure Kelvin and Jose (perhaps even Morgan once he calmed down) helped steady things out. What characters like that do they have left? (legit question by the way I am sure they have some)
Their main links seem to be with Janssen and Wijnaldum. They play in the positions of Lukaku and Barkley. That is not a recipe for progress unfortunately, just transfer profit (and therefore not spending all the 160m).
Finally as already alluded to since their transfer budget has been shouted all over the papers they face the risk of being substantially overcharged for anyone proven. You only need to look at Man United's latest Defender target (about 25 career games, rumoured fee of £32m) to see what can happen when everyone knows you are A). Desperate and B). Have money