I asked David Pyke the same question. Here is his answer.

When entering real-life transactions to be applied throughout a replay you should make the transaction date and the effective date the same. You can enter an effective date when you create a transaction retroactively, for example, placing a player on the disabled list retroactive to the last game he played, but the effective date is only used for reporting purposes. The transaction will not be applied until the transaction date passes.

Cubsjunkie

WAY TO GO BLACKHAWKS