User blog comment:B214/Volume 23 discussion blog/@comment-1884090-20170408001538/@comment-31137559-20170410215820

Well you do need power and strength to back up those tactics you might have. Tactics are enough to win the battle, but are they enough to win the war? And some things you won't be able to foresee. Was it possible to foresee Sairaorg's bishop activating his Sacred Gear in between the Glasya-Labolas match and the Gremory match? Being a king doesn't mean you have to foresee every move the enemy might make. It depends on how the king and the servants react to their opponent's move. And Issei giving the girls Dragonar armor wasn't really a work-around. It was Issei acting as a support and giving them a Boost. It's not really covering up their limits. They are already overpowered as it is, the armor just makes them even more so.

And theiretical preparation would do some good. Although that could have done Rias some good instead of taking Sairaorg's peerage for granted. They knew they were really powerful, but they basically saw Sairaorg as the only threat. And it nearly cost them. Rias would have retired had Issei not used that Phenex Tear on her. They mostly underestimated Sairaorg's peerage and it cost them although they were able to come out on top. Rias and her peerage have gotten overconfident just because they are very overpowered and don't bother much with the theoretical side. They never wondered what if this happens. They were basically no different from Riser at the beginning who thought he was immortal because he was a Phenex and we saw where that got him. While Riser did win the Rating Game, he lost all but two of his servants to a rookie peerage with a king and only five of her servants. And only his queen took down Akeno, Kiba, and Koneko. It's not that hard now to imagine why Riser was overconfident and thought he was immortal because he had won all his Rating Games up to that point. I know Rias is a good king and has good servants. But she has gotten overconfident and underestimate her opponents to an extent because of her powerful servants. Now I hope she doesn't make the same mistake, but I doubt it, but she hasn't fought anyone of note yet. We'll see during the Rias vs Vali match.