>>109352932He didn't magically became good.
At first he gained control of his specific abilities because, as they constantly told him, he had to relax and focus. Which he only was able to do after he sorted out his personal problems with his father.
Then, when he first put on the black outfit, the music and directing made it seem like this is where he shows off how awesome he is now, but he was still falling down a few times on his way to the collider. Then when he was there at the climatic battle he was quite good, but remember what Peter said near the beginning of the movie: You learn fastest when you're near death danger. In other words, it was foreshadowed.
My personal problem was that not only has he all the same powers as the others, but ALSO two additional ones. If he weren't still a newbie in this movie, he would so overpowered
