The defence starts when your opponents have an outlet ball starting from their defensive line. Mainly when the ball is in their defensive third.
A - For the 3-2-3-2 defence the two forwards stand in the inside channels, threatening the pass from the full backs to the inside, midfield channels.
The three midfield (Left Wing, Link Forward and Right Wing) stand in the empty channels behind the two forwards and cover the centre and outside channels, making it difficult to see a clear pass.
The two screen players can zone mark the inside channels, behind the midfield and the three backs can man-man mark.
B & C - The 3-2-3-2 press is designed to put pressure on the outlet ball and force the ball to the half backs, so they can be trapped in a second phase team press to the sidelines.
When playing against a 4-3-3 formation this press is ideal, especially if you know that the opponents key players in the defence are out in the centre channels. However the benefit of this formation vs a 4-3-3 is that all the positions are clearly covered.
LW takes RH
LF takes the RB
RF takes LB
RW takes LH
LF takes CM
LS and RS zone mark and take midfield players
Backs man to man 3 forwards
The front 5 players need to be giving the perception that they are covering a wide area and that they are ready to intercept any pass that is played through the centre channels. If these players are static and upright then the ball will easily pass between the middle three,
leaving the defending team exposed. The midfield three must not be flat, as one ball through a channel could eliminate 5 players (3 midfield and 2 forwards) if it does get through. The help side wing and link forward should alter their position when the ball is on a side, creating
a shallow V shape.
The backs must be tight man for man marking because there is no pressure on the ball from a centre forward, which leaves the long aerial ball to forwards a threat from the opposition.
If the defence isn't mobile and do not work together to trap the ball at a sideline then the system can be exposed with clinical passing, especially on 45 degree angles.