I can't remember, but did the PS4 lose April 2015? If so, your inquiry is spot on. If not, well, then it gets a little more complicated, but I'd be inclined to agree with you still. Really, April isn't the best month to make those claims (that Switch is losing momentum). It also doesn't have the caliber of releases that it did during this time last year, so I'm not sure what people expected.

I see it as a natural order of things, while the PS4 is seeing those numbers because one of its biggest releases just launched. 

Yeah, couldn't remember. Just goes to show that people jump the gun far too often.

Regardless if it's Switch or PS4, 175k is pretty dreadful. Especially if the console is expected to sell a ton.

Because the sales were so poor for PS4 in its 2nd April it even lost the month to XB1. While we didn't expect Switch to beat PS4 with GoW month, I personally expected 200k+.

All 3 consoles exceeded my expectations last month, but only PS4 did that this month. PS4 might be strongly up YoY in US, but its probably down YoY  for everywhere else leading to Sony's expectations of lower shipments.

@Miyamotoo
I don't know about without a problem, because 20m in a year is a lot for any system. Smash couldn't do much for WiiU obviously. But at this point I have no particular reason to doubt Switch will reach its projection. But I think it's safe to say that Switch will primarily be driven by those type of core quality games, unlike the Wii where a substantial amount of people bought it for motion control titles like Wii Sports.
So it will be interesting to see how these games push Switch sales especially in its second year, when stock shortages aren't the issue they were in 2017, so it's easier to gauge how much interest there actually is.

But even without those 175k for PS4 in 2nd April on market, best previous month before this April with GoW was 206k for PS4

Hence the expectation for 200k+. XB1 2nd April was 187k, so Switch is last out of the 3 consoles for the month. Sure it isn't far off, but I expected more, considering the trend of Switch sales.