From Pilot_51's Wiki
How much deviance to add for moving (walking/running):
x - maximum deviation to add y - how much to add for each move forward/backwards z - how much to add for each strafing move (moving sideways) w - how much to reduce per server-frame (30 fps)
All x-values (maximum deviation) of SetFireDev, SetMiscDev, SetSpeedDev, and SetTurnDev are added together.
Source and more details