I've said it a million times here, but there is zero evidence that "wave" midterms affect gubernatorial elections.
How, though? Just looking at simple data such as which party controlled how many govs offices each year is practically enough on its own:
https://en.wikipedia.org/wiki/Political_party_strength_in_U.S._states
As soon as a party assumes control of the White House for multiple terms (sometimes just one), the balance of power in the states shifts against them. The only exception there is the 1930s, which saw a national repudiation of the Republican Party for its failures during the GD. The Solid South is also an exception, but mostly because it was a one-party apartheid region.
All elections have some exceptions depending on the trends of the time and unique local factors, but the white house party generally gets a lot less of them.
The only Democratic pick up from 2006 that was lost in 2010 was Ohio. The only Republican pick up from 2014 that was lost in 2018 was Illinois. 1994 is the worst offender, with five 1990 Dem pick ups turned into single-track Governors.
With your other post, you're mostly making a case for incumbency here. It's perfectly fair to say that many voters often judge gubernatorial candidates differently, and because there's so much attention on those races, it's harder for parties to score tons of pickups like they do further downballot, where most voters in recent times have basically started voting for parties, not people
(with some exceptions). I still think that wave elections tend to energize the out party, which brings out many voters who are less inclined to split their tickets. That makes it harder for gubernatorial candidates running for open seats, or incumbents who are not well-liked or are not really well-known by the electorate. Like, if we replayed MA-GOV 2014 in 2018, I'd say it is more likely than not he loses, and never is able to use the office and his higher profile to establish himself as a popular executive. In a way, wave elections give parties in difficult states the chance they need to get their foot in the door and make a name for themselves.
