The 9mm allows for both higher capacity and velocity, and also offers lower recoil, which reduces barrel rise and can improve accuracy in stressful situations. My guess is that the officers in question need not only more time at the range, but a refresher course in tactical defense.
I find my .45 1911 has less recoil than the browning 9mm high power I used in the army. The 9mm has a higher velocity, whereas the .45 is subsonic, I find the 9mm has a sharper recoil, and the .45 comes back onto target quicker.