If you've picked LangChain over CrewAI (or vice versa) partly for "security reasons," this preprint is worth five minutes. I ran a controlled evaluation — 6 LLMs, 6 agent execution conditions, 5 attack families, 7,020 payload-verified trials — to isolate what actually explains security outcomes in agentic AI systems. The headline: framework choice explains about 0.06% of the variance (not statistically significant, p ≈ 0.70). Attack family explains ~29%. Model explains ~4%. In plain terms:...