In this talk, I will discuss the role of the strain matrix in the Navier-Stokes regularity problem. First, I will go over an identity for enstrophy growth in terms of the determinant of strain, and a regularity criterion in terms of the positive part of the middle eigenvalue of the strain matrix. Then I will prove the existence of finite-time blowup solutions for a toy model of the strain equation. By treating the full Navier-Stokes equation as a perturbation of this model equation, I will show how we can obtain a new conditional blowup result for solutions of the full Navier-Stokes equation.