The change to defensive mentality is as a precaution if the game is evenly matched or if u have a slight edge. I suggested already that against smaller teams who u expect to play on the long ball, change D-line to drop deeper and no offside trap. Use this only if you notice in the beginning of the game that your defenders are being caught out with long balls. Having fast CBs help, balanta and mbiwa would make a great pair.
I actually have a formation pre-saved with instructions changed to drop-deeper/no-offside but change mentality to control as i expect the small teams to fall back and absorb pressure allowing more space for my attackers to go forward.