In PSF, you can customize your blitz on any play. You can blitz any linebacker (or all of them) and can usually blitz the Weak Safety, unless he’s covering a receiver.
For convenience, the screen also has two big text buttons, “Everyone” and “No One” for quickly turning all the men on or off.
Blitzing serves many purposes (besides just being fun!). It usually disrupts the offense’s timing and puts more defenders along the line and in the backfield.
Blitzing can certainly be used to disrupt passes, because it increases the pass rush, and quarterbacks generally prefer having time to set up and throw. Blitzes can increase your chances of sacks, incompletions, or even interceptions.
Blitzes can also mess up their running game, since you can blitz a man right at the point they’re attacking. Blitzers can increase the chance of fumbles, especially if the back is hit in the backfield.
However, blitzing does have risks, since you’ve now reduced the number of defenders you have downfield, increasing the chances of breakaway runs. Short passes are particularly dangerous against blitzes.
In short, blitz to break up runs, screens, and long passes, or to increase the chance of causing fumbles, but don’t blitz if you expect short passes or trap plays.