If there is a wave election in November, gerrymandering backfires and ends up losing you more seats than you hope to gain through it. You pack the districts so that you win with 55% to 45%, except for a district here or there which will go 10% to 90%.
In a wave election, it only takes a shift of 5-6% in those gerrymandered districts for them to be lost.
You are pretending that a 'wave election' is a thing that people decide to do, instead of a label applied after the fact as a descriptive aid after the occurrence of the circumstances you describe. In other words, this is circular logic.
In practice, heavily-gerrymandered districts rarely swing parties, and when they do, they almost always swing back.
You are pretending that there aren't circumstances that have an observed relation to systematic deviations from median election results that people can observe to understand that a wave election is more likely to happen in a particular election.
If there is a wave election in November, gerrymandering backfires and ends up losing you more seats than you hope to gain through it. You pack the districts so that you win with 55% to 45%, except for a district here or there which will go 10% to 90%.
In a wave election, it only takes a shift of 5-6% in those gerrymandered districts for them to be lost.