Hypothetically, (as it most likely won't be explained away in the movie), could we write off the aliens in "Requiem" as being genetic freaks altered on a genetic level by the Predators for the purpose of being game? Who's to say that the following was not a actual sequence of events:
-Queen is kept in stasis by Preds in arctic temple. Queen and/or eggs are injected with some sort-of Predator steroid to expedite the creature's growth cycle
-One of the genetically-altered face-huggers gets it in on with Scar, the bugs off while he's passed out
-Scar gives birth to PredAlien "Chet." However, because of the predator tampering, Chet grows in size in comparatively short matter of time and wipes out Pred crew
-After crashing outside Gunnison, the PredAlien, because its genes dictate the need to propagate as quickly as possible for the sake of the hunt, manifests a new, alternative method for reproduction; the highly-reviled "barf & birth." This is not part of the normal xenomorphs' life-cycle, but is a new addition to the PredAlien's genome; in an area with no queen and few other aliens, the preds program the alien to supply game as quickly as possible, hence our new bulimic fiend
-The PredAlien spits up in the mouths of assorted towns-folk. Towns-folk give birth to various, (and possibly multiple) chest-bursters. However, the new breed of aliens are comparatively slow and uncoordinated compared to other members of the species encountered by humanity/the audience. This is because the aliens that over-run Gunnison are not true Xenomorphs, but genetic aberrations born from another genetic aberration, the predator's genetic enhancements speeding their life-cycle but at the expense of their senses. They're literally copies from a copy, resulting in the sluggish behavior and comparatively less-than-stealthy mannerisms we've seen/heard about.
-Wolf easily kills the crappy "Instant-Aliens." Gunnison obliterated. Pizza-Boy skewered through the back. Dallas and Kelly move to Elm street and have a baby boy named "Pussy-Face." Chet realizes she has a problem and checks into a clinic for help. While there, she meets Lindsay Lohan and promptly bites off her head.
It's just a theory, (and one that, as stated before, will not be in the movie), but since I doubt the movie will contradict it, this, (or something similar), could be used to explain away the xenomorphs' lack-luster behavior/appearance as seen in "Requiem": essentially, genetic deterioration.
