Hindsight is 20/20, but those decisions in the moment made tactical sense. And the first four subs were all made to protect a 1-0 lead rather than try to build a 2-0 lead.
-Aaronson was a pest and quite active in winning the ball back. I'd hate to think what Wales could have done with a few extra possessions had he not been subbed on. This move also insulated Weston from picking up a second yellow or aggravating his quad injury.
-Dest was also sitting on a yellow and was leaving too much space behind him for a team with a one goal lead; Yedlin made sense as a more defensive-oriented RB.
-As much as I don't like Acosta's overall skillset, his soccer IQ is high and he preserved the draw with that yellow he picked up late preventing Bale from shooting on an open net. Also, Musah got more sloppy the further the game went on and was an obvious choice to come off.
-Haji for Sargent is the one that I don't fully agree with. Yes, Sargent had been invisible the whole second half (and really the last 20 minutes of the first half too), so the thought of swapping in a big target forward who is better in hold-up play makes sense. But, Christian had been getting beat up all match and was getting more visibly frustrated the further the match wore on. I'd be tempted to sub Gio for Pulisic here, but I also can understand not wanting to sub out all of your ball handlers in a match that you are winning based largely on controlling possession. This is the tough one. I think I would have kept the fourth sub in my back pocket to see how the match continues to evolve.
Now fast forward to the 88th minute, and your final sub in what is now a tie ballgame. You need to both protect the draw and also push for a goal. What was effective early in the match? Wales was content to sit in a five-man backline and wait for counter opportunities, and early indications after Bale's goal was that they would do that again. So you need a sub that helps you play more direct, not a sub that helps you string together a 14-pass goal that takes 5 minutes to set up. Morris has his flaws and shortcomings, but that is the exact role he was brought on the team to fill. He's got straightline speed to beat the backline and the strength to hold off a 1v1 defender and allow time for trailing runners into the box. Perhaps he should have come on for Pulisic rather than Weah, but then we would have been forcing Acosta and Aaronson into the playmaker role. We needed both a player on the pitch that can make the line breaking pass (Pulisic on dead legs or Gio) and can make the run behind the backline (Weah on dead legs or Morris). Really, we needed one extra sub available to us at this point so we could have brought Morris and Reyna on for Weah and Pulisic. But we only had one sub left, which makes me second guess the earlier Haji-for-Josh sub.