This suggestion can be defined to be more whole but it will cost in complexity.
Hence, I suggest this one which is simpler, but add enough for the common cases.
The suggestion is to allowing a different deffence strategy for the starters and the rest of the players.
This will allow users to use a different deffence combination. One that is suiting the starters and one for the startups.
There are games where you can supprise your opponent with a C that will play as a SF and create an advantage but will defend the C, but his backup can only play the C or the SF good enough (for example).
When one of those players that is "cross" deffending is sent to the bench, the deffensive strategy for him and the other player will be upon the backups.
An example:
Starters (Main) deffence strategy: PG Defending SG, SG => PG, SF => PF, PF => C, C => SF.
Backup deffence strategy: Regular (PG=>PG, SG=>SG, SF=>SF, PF=>PF, C=>C).
When one of the cross defending players (C, PF or SF) is replaced, the backup strategy will take place for that group.
In other words, the deffence strategy will be changed into: PG Defending SG, SG => PG, SF => SF, PF => PF, C => C.