Sure, but you're ignoring a more complicated bit of logic.

Specifically, the idea that a portion of game sales are basically proportional to system install base at release - that is, with the Wii U and PS4 at similar install bases, launch sales of both games would end up being something like A + B*I + C*S, where I is existing install base, S is sales boost for the system, and A, B, and C are constants for each of the two games.

If we make this supposition, it's entirely plausible that the difference in drop in hardware is comparable to the drop in software sales.

To put it another way, you're falsely assuming that the baseline now is the same as it was prior to the release of the games.

In practice though, that's not gonna happen.

I mean, we've seen this happen a million times here on VGC, consistent historical data is more meaningful than pure mathematical speculation.

So you're saying that it's *not* just about maths and logic?

Last week it was a narrow vicorty for PS4, topping Wii U 201630 to 187028 (14602 units), or outselling it by 7.8%.  However, the key PS4 title/bundle was Watch_Dogs, which released earlier in the week than Mariokart 8.  Early info from the UK indicates Watch_Dogs on PS4 is down 84% while MK8 sales are down a less dramatic 76%.  If this carries over to hardware - and is a wordwide trend - we could see Wii U drop less than PS4 (by about 10%) and edge out a narrow victory for the first time.  What do you think... will this happen?