The only one that looks odd is the first one because of the angle. I assume he never had the handoff because it just flies out of there.Here are some videos of the 4 first half fumbles.
You can argue that a couple of them would have been overruled, but I'm not sure I agree,
But I don't know know how anyone can argue with the point that those fumbles came out of his hands VERY easily. I don't see any secret fumble-causing action by UCLA.
The man has hands the size of softball gloves. He didn't drop passes and didn't fumble, until .......
The second looks like his knee was down and the third probably could have been ruled incomplete, but still hand got in there. Just like the last one. So if it were intentional he had to wait until just the right play?