Couple things on this. Pulisic waves off the substitution but only to take the DFK. Who else is really taking that and going to be more dangerous than Pulisic? With that, it is exceedingly rare to make a substitution in that type of attack situation or on corners. I have refereed many a game where there are subs waiting to come into the game and I look and call for them and the coach doesn't want them in the particular situation and will wait for a goal kick or throw in. And I should remind everyone, the actual laws of the game say a substitution can occur on any stoppage of play at the referee's discretion. It doesn't have to be on your throw in or restart in your favor. HS and college rules are slightly different in that it has to be your throw in or corner to make that substitution.
This is important to note and it is true for any team sport. You can have a great collection of talent but if they don't mesh and actual work together they're going to struggle. The biggest problem with the US right now is there is no big personality who can also be a leader. McKennie is a big personality but I've never viewed him as a leader type. ream could be that leader but you don't even know if he's going to be part of the squad going into the WC. Really, it needs to be Pulisic but he has issues getting himself pumped up for games so it's hard to see him being the guy that gets on others for not playing with enough focus and intensity. He almost sort of checks out of games if he is not able to get involved early on. Adams....maybe but he needs to stay healthy. Not Weah. Musah has the intensity but not the discipline to lead. Quite honestly, the person I constantly think of as an actual leader in terms of US players is Christian Roldan but he's not likely to be used on the USMNT again.