Actually, it's not just that it sold around 1/3 of its total sales this week.
Famitsu
Week 9, Switch's debut
30./06. [PS4] The Witch and the Hundred Knights 2 # <RPG> (Nippon Ichi Software) {2017.02.23} (¥7.200) - 2.728 / 18.437 <40-60%> (-83%)
Week 10
30./00. [PS4] Minecraft: PlayStation 4 Edition <ADV> (Sony Computer Entertainment) {2015.12.03} (¥2.400) - 2.307 / 189.677 <80-100%> (-5%)
Week 11
30./27. [PSV] Minecraft: PlayStation Vita Edition # <ADV> (Sony Computer Entertainment) {2015.03.19} (¥2.400) - 2.763 / 957.387 <80-100%> (+0%)
It actually had its best week at retail since the console's launch
Moreover, adding a comparison with other digital games released on Nintendo platforms that saw retail codes on shelves
Kirby Fighters Z {2014.7.23}
Sales from Week 30, 2014 to Week 35, 2014 - Retail: 11,586 | Digital: 43,684 | Total: 55,270 | Retail share on overall sales: 21%
Pokèmon Battle Link! {2014.3.12}
Sales from Week 11, 2014 to Week 13, 2014 - Retail: 10,585 | Digital: 30,235 | Total: 40,820 | Retail share on overall sales: 26%
Great Detective Pikachu {2016.2.3}
Sales from Week 5 to Week 8 - Retail : 5.471 | Digital : 21.749 | Total : 27.220 | Retail share on overall sales: 20%
SnipperClips: Cut it Together! {2017.3.3}
Sales from Week 9, 2017 to Week 12, 2017 - Retail: 10,062