I don't know why, but I love how Sentinel crawls on all 4 while transforming. It just looks pretty cool.
Yeah, "crawling" seems so lame. "Diving" at least makes it seem more dynamic. I think it has something to do with the fact that in both instances, his intent was to quickly get away and drive. Bracing himself with his hands allows for easier transition to vehicle mode. "Hitting the ground running", if you will. But seriously, it makes sense to do that. Strikes me as the same thing that Ironhide might do if he were to transform and attempt to drive away. If he didn't use his hands/arm to brace himself, what would he do? Dive head-first into the concrete and then have the wheels fold up and drive away? I was very surprised that we didn't get a big IN-YOUR-FACE epic transformation by Sentinel. I thought for sure we would, given that he was a main player with a sweet design.
Too bad we barely even saw his transformation at all. Wouldn't be surprised if it involves a lot of cheating.
I felt that Sentinel's transformations were sloppy. They weren't as complex as some other bots and cons. His transformations weren't up close and you don't really see how it happens.
I just liked how he just fucked shit up and then just transformed and left. I think he did that twice in the movie. Reminds me of how Starscream flew in the first movie, fucked shit up and then transformed and flew away.
Just so you guys can get a better look at Sentinel's transformation, here are two GIF images that I made. Sentinel Transforms Sentinel Transforms_2