Q&A: Strategy Rating

Q: May an army's Strategy Rating change in mid-game, or is it fixed for the duration at the start the game? For example, a Space Marine force would have a Strategy Rating of 5, but this decreases to 4 if they included any Imperial Guard units or Titans in their army. Would the rating increase to 5 again if all Guard units and Titans were destroyed in the midst of a game?

1. The Strategy Rating is fixed for the duration of the game, regardless of casualties.
2. The Strategy Rating may change if casualties reduce a "mixed" force to a "pure" force. (Change the rating at the beginning of the next turn, or the beginning of the next phase?)

A: This is a question I can't honestly remember coming up during playtesting. This makes me think that if it did ever occur (and I think it must have), then we didn't notice and kept on playing with the same Strategy Rating we'd been using since the start of the battle. However, players that prefer to come up with their own house rules for such situations should feel free to do so, as I can see no good reason why the Strategy Rating should 'not' change from turn to turn depending on the composition of the army.