The IC is the PE42542, a SP4T RF Switch, 9 kHz–18 GHz. It comes in a LGA package with 4 separate ground pads, different pin dimensions, different number of pins on each side, and different pin pitches.
Why is this footprint so asymmetric in pitch and pad dimensions? From this vicor application note, I have observed that the pads are different sizes depending on if they are I/O or power. For the PE42542, I have noticed that the smaller pads (2,7,12,22) are the four RF outputs, while the large ones are GND. I've also noticed that the pins on the IC are grouped with respect to function. However, I would still like to know why Peregrine could not have picked a standard pitch and pad size. It would make building the footprint a lot easier!