Fair enough. I think it was down to the foundation being laid down by Moyes. The club was an established top 6/7 PL side back in summer 2013. Once the new idea had emerged and the old drill was taken away, the effect appeared after a year.
The current situation is a bit different. Koeman has improved a team that was a bottom half PL team for two conservative seasons. Of course, the second season will be a great challenge for Koeman but judging by his pragmatic approach to the game and his men management, we should be optimistic, knowing or assuming that there shall be a good budget at his disposal this summer. Whether he can break the glass ceiling will depend on the amount of the said budget.