It's a weird, weird inconsistent universe.
Movie 1 and 2, TFs arrive via burning 'Rocklord' modes.
Then in Movie 3, they have ships - the Ark, the Xantium (that brought the second wave of Autobots, apparently).
In Movie 4, most of the original Autobots have just disappeared, replaced by a new crew that came from *never explained*
And now in Movie 5, we're back to burning Rocklord arrivals.
Did the writer's room just sit around get drunk and stoned or what? Or did they actually come up with a bunch of really sweet ideas, and Bay just went 'f--k it, that's too much plot, I'll write my own'.