If not even God can do the logically contradictory, then it becomes a possibility that even he may be forced to make tradeoffs in order to maximize the good, and the problems we see are the downside of those tradeoffs. Now this possibility may be unlikely because we can think of alternative scenarios that would seem to produce less suffering than we see. The catch, however, is that we don't necessarily have the capability to fully trace out the results of the scenarios to see if they have hidden problems that would actually make them worse than our current one. This means that it is difficult and perhaps impossible to establish that the presence of evil really does contradict the idea of an omnipotent, omnibenevolent God.