The tactics changed with the injuries pretty significantly, they had to. Jóhannsson wasn't in a position to succeed, though he could have made a couple better runs late in the game, he had no support. Dempsey wasn't near 100% after getting his nose kicked in and Besler's injury led to an even more defensive stance than usual.
I don't think Jóhannsson is at a stage of his career where he can be a game-breaker at this level, but I do think he has the speed to create chances. Wondolowski is at his best when he's being fed shots, and I don't think we're going to be able to do that too often against Portugal and certainly not against Germany.
Wondolowski did look good in friendlies against World Cup teams South Korea and Mexico earlier this year, so I'm far less terrified of the prospect of him playing as I was before...but I still don't have faith in him being able to create space for himself against elite teams.
Dempsey and Jóhannsson could work in a 4-4-2. That's the formation we started with against Ghana, but after Jozy's injury Dempsey spent a lot more time in the midfield than up with Jóhannsson out of necessity. Having any of our forwards as the lone striker is a recipe for failure.