If we don't have a good defense, we won't be competitive in the premier league. Getting results like 3-2, 4-3 etc is not sustainable. Palmer is the star right now but you can bet going into next season that he will definitely be aggressively marked by the opposition players and they will start the tactical fouling (just like how teams used to go for Hazard with those nasty challenges).
That would mean we remain in 10th spot for 2+ seasons and there is every chance players will start to leave without European football.
Poch isn't the answer, he can help in the short term but if we want to get back to being in the mix for top 4, we need a better manager and a much much better defensive structure.