That's been pretty much the truth for every single Switch game sold so far. COMG numbers almost never gives away anything about a games performance for the Switch.

Taken from https://www.resetera.com/posts/10174495/

ComG! Week Sales, 2018 (Jul 02 - Jul 08)

01/02 [NSW] Minecraft - 45 pt (-3 pt)
02/01 [NSW] Mario Tennis Ace - 33 pt (-33 pt)
03/ N [PS4] Zanki Zero - 26 pt
04/ N [PSV] Zanki Zero - 19 pt
05/04 [NSW] Splatoon 2 - 18 pt (=)
06/13 [NSW] Mario Kart 8 Deluxe - 11 pt (+6 pt)
07/09 [PS4] Fate/Extella: The Umbral Star Link - 8 pt (+1 pt)
08/03 [PS4] The Crew 2 - 6 pt (-16 pt)
09/10 [NSW] Kirby Star Allies - 6 pt (=)
10/ N [PS4] Far Cry 3 Classic Edition - 5 pt
11/20 [NSW] The Legend of Zelda: Breath of the Wild - 5 pt (+2 pt)
12/15 [3DS] Pokemon Ultra Moon - 5 pt (+1 pt)
13/ R. [PS4] Jikkyou Powerful Pro Baseball 2018 - 4 pt
14/12 [PS4] New Gundam Breaker (Build G Sound Edition) - 4 pt (-1 pt)
15/ R. [NSW] Sumikko Gurashi: Sumikko Park e Youkoso - 4 pt
16/ R. [PSV] Grisaia no Kajitsu: Side Episode - 3 pt
17/ R. [PS4] Utawarerumono: Chiriyukusha e no Komoriuta (normal version) - 3 pt
18/ R. [PS4] Persona 5 (normal version) - 3 pt
19/08 [PS4] Detroit: Become Human (Normal Version) - 3 pt (-4 pt)
20/ R. [PS4] Horizon Zero Dawn Complete Edition - 3 pt

Minecraft still getting a lot of points on COMG but that hasn't translated particularly well on the MC charts thus far. Zanki Zero never even made the pre-order charts but it was good enough this week for 3rd/4th on COMG weekly.

Wow, that weekly chart, ouch. All the way down to 3 points. They can't be selling more than 250 game copies a week nationwide then. I knew they were small, but geez. VGChartz makes a list of the top 75 each week, but I doubt COMG sells 75 different games in a week if the top 20 goes down to 3 copies.

Yesterday's chart:

Great day overall

Oh wow oh wow Toad, racking up dem points

Toad fucking them shit up in serious fashion! Go little dude!