If there are key uncertainties that limit your ability to make a good estimate of how your capacity and resources will affect the extent of strategy impact, then create alternative maps that capture different versions of the area of uncertainty.
For example, if there is a policy strategy that requires support from the ruling party, but there is a major election due 6 months into strategy implementation and we have stronger relationships with one party than the other, it may be difficult to represent how our capacity will affect strategy scope. In this case, you might create one map for the case when one party wins the election, and another map for the case where the other party wins. You could then see in the next step how much the outcome of the election would influence the strategy’s overall impact, and decide if the risk was acceptable.