A plane flew over England's St George's Park base on Saturday, with the message "Most Croatia goals come down the left apparently" trailing behind it. The message seemingly was referring to Southgate's decision to take four right-backs in their original 26-man quad. England open their Euro 2020 campaign against Croatia on Sunday.
Earlier on Saturday, De Boer was also receiving advice from the skies. The former Atlanta United boss has come in for criticism for playing a 5-3-2 system in their two warm-up games, when Netherlands teams have traditionally played a 4-3-3, inspired by Johan Cruyff's Total Football.
The plane circled above the KNVB's training complex in Zeist, dragging a banner behind it with the message: "Frank, just play 4-3-3."
The Netherlands squad were training at the time and many laughed when they saw the message. All 25 players were out on the field -- including the injured Matthijs de Ligt -- and took it in good humour.
It remains unlikely De Boer will bow to supporter pressure. He has used the 5-3-2 against Italy back in October 2020, and then again in their two warm-up matches in June. They drew 2-2 draw with Scotland, and then beat Georgia 3-0. After that win, he said the tactic is an "excellent system" for the players they have.
However, captain Georginio Wijnaldumm said in an interview with Voetbal International he prefers playing in a 4-3-3.
"Look, my heart is just 4-3-3 with me in an attacking role," Wijnaldum said. "We had a good time under Koeman, although I still think that this was also due to Frenkie de Jong.
"I have nothing against 3-5-2 or 5-3-2. Then there is also room for me, but it takes a lot of strength to always get there. You miss an extra attacker, that will have to be a midfielder then. But it's not about me, it's about what it takes to get a result."
With Ukraine up first for the Netherlands on Sunday in Amsterdam, De Boer and Oranje are under pressure to open the campaign with a win, having not played in a major tournament since 2014.