The biggest problem, I feel, is that the character contrast they were trying to set up simply does not ring true. We've seen Pike out-think and out-maneuver tactically superior foes and unleash hell without hesitation against the enemy in space battles on two different shows, now. The "mistake" the episode forces him into feels... well, forced. And the resulting lecture from Kirk would've felt unearned even coming from an actor who could remotely match Mount's charisma (and I'm sorry he's getting so much flak, but let's face it, Paul Wesley is just not that guy).
I can't think of a way to fix this episode, really. I would have loved to love it, a "Balance of Terror" what-if looks on paper like it would be right up my alley, but there are just too many pieces here that don't fit, too many elements that don't land. As regards everything from story and heart to character studies and thrilling space battle tactics, "Memento Mori" has this outing beat by a mile for my money. (Admittedly this is also partly because I am not wild about SNW dwelling repeatedly on Pike's Impending Doom, much less about a storyline that's totally driven by it.)