Several issues firstly the style is slightly different. Poch is at heart more defensive than Klopp, Poch wants to press and play with intensity to stop the opposition playing as much as to score, Klopp wants to play hard and high to simply out score the opposition. Personally I think Klopps way in some respects is more Spurs in the traditional sense of scoring more than the opposition and being reckless to a degree. That being said having a top notch defensive record for a Spurs team is amazing.
If anything I think Poch has pushed some of our players as far as they can go. He has improved us massively as a team but we need more quality mainly in attacking areas if we are too move to the next level, that therefore is not a change in manager but the purchase of a few top quality players.
People forget that while Spain may have the best individuals (Messi, Ronaldo, Modric, Iniesta etc) the Prem has the best managers (Conte, Klopp, Guardiola, Wenger, Mourinho, Koeman and of course Poch) so its got to a strange situation where if any of these guys don't win things they are deemed failures when in reality it's simply that there is so much competition and it comes down more to the quality and depths of the squads which lets be honest we need to improve on.
Yes Poch not having won anything was also a minus for him, but it's pretty obvious if he'd stayed in europe a few more seasons he would have picked up some trophies as the competition is so much less fierce and then he would have been well beyond a team like Southampton. And probably us as well, to be fair.
I agree we need better players and while I admire his commitment to pushing through youth and essentially keeping the England squad afloat in the process we are going to find it hard to break out of 5th or 6th until we can spend big. The current situation is that we can splash out £30million on players but it's basically just exchanging like-for-like in our team and doesn't really improve us any great deal. To get the next level we have to spend even more than that. Which isn't going to be happening for a few years at least.