If you want to make the scenario more realistic then put more time pressure on Voldemort or put him under more cognitive stress some other way. The hardest part for Voldemort is solving this problem in a short time span and NOT coming up with a solution that foils Harry. The reason experienced soldiers/gamers with little to no intelligence still win against highly intelligent combatants with no experience is that TIME matters when you're limited to a single human's processing power. In virtually every combat situation one is forced to make decisions faster than one can search the solution space. Only experience compensates for this deficit to any measurable degree. In this situation there are several aspects that Voldemort does not have experience with. If he must spends his cognitive resources considering these aspects and cannot draw from experience it makes mistakes much more likely.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 114, and also, as a special case due to the exceptionally close posting times, chapter 115.
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)