When simulating a live game (i.e. not using the multi-day simulation in the calendar), you have the option to set your team’s forecheck. It affects the sim and how your team attempts to get the puck when the opponent has possession, especially when the opponent is getting out of their d-zone. Below is an overview of the different options available.
Has a chance to force more turnovers resulting in more scoring chances at the cost of making your team a bit more vulnerable in the neutral zone. If the opponent’s d-men manage to “escape” the forecheck, it generally results in an easier transition through the neutral zone for them. There’s also a chance for the opponent get on a breakaway. All that depends on how good their d-men are with the puck (mostly the passing attribute), how good your forwards/d-men are (skating, checking…).
Passive forecheck, where your team does not actively puts pressure on opponents in their d-zone and uses kind of a trap in the neutral zone (can be used to simulate something like this tactic shown by Tampa). It usually forces the opponents to dump the puck in, resulting in more puck battles in your d-zone. It can be quite effective and usually results in a fewer total shots for the opponents. Wouldn’t probably be very fun hockey to watch in real life though.
Somewhat balanced option between conservative and aggressive, with some pressure applied by one or two forwards.
The forecheck for your team is controlled by the CPU. Usually starts the game with moderate, switching to aggressive later on if losing or have a low shot count. Conservative is used mostly late in the 3rd when leading. The automatic option also controls whether a goalie is pulled or not when losing late in the game.
Multi-day simulation always uses the automatic option for all teams.