Because Ten Hag had a very difficult season at Man United, it was felt that he was considered a bad coach. And especially as Xabi's replacement, it would certainly be considered very bad if he couldn't deliver the best results.
Unfortunately, in this opening match, Ten Hag was actually embarrassed by being defeated by Flamengo U20, even though it was a friendly match.
Source: Full-time in Rio 90+4' | 5-1Wait, so this is true! I was scrolling down on Facebook and saw a post by Fabrizio on his page were he posted, Flamingo U20 4 Vs Bayern Leverkusen 0 HT, like four goals to nothing against Leverkusen and it's not even their main but by the U20. I went online to check to confirm if it wasn't a prank by Fabrizio. How really did this Leverkusen side turn out like this under Ten Hang, it might be just a friendly match but common, against U20's?