Exactly. Parker + the system is good enough against 27 teams, but not the 2 that stand between them and a championship.
It's the same thing always every time they play them, especially on the road: It's a grind offensively, Duncan struggles mightily, Ibaka is all world, a few of their role players join him in playing out of their mind and they win despite Westbrook struggling mightily.
The issues will probably remain the same no matter what tweaks are made, but the coaching staff needs to come up with something in the next meeting. Generally, you save that type of thing for the playoffs against this caliber of opponent, but in this specific case, they need to make an exception. It's more important to get a better idea of whether they can beat this team in a series with their current personnel.