Sure! 
Okay. I did, a little bit. But I'll thrown in a few more details.
Anyway, is it me or does it look like this is what they did for Ash's eyes
for XY in comparison to Best Wishes?
BW:
Ash's eyes (and overall design) get updated to Ken's Sugimori's current artwork
and are visibly brown from now on.
Ash's eye models are designed/animated "from scratch" from here on out in every episode.
XY:
OLM finds Ash's previous eye design from OS - DP,
uses them on the model for XY Ash, convert his OS-DP eye design
to match the BW better (as opposed from drawing them from scratch),
then stretch out his "black eyes" just slightly to add in the brown coloring again.
In a nutshell:
BW:
Eyes are totally redesigned.
XY:
Ash's black eyes are simply edited to be brown
with slight width added to them.
Okay. I did, a little bit. But I'll thrown in a few more details.
Anyway, is it me or does it look like this is what they did for Ash's eyes
for XY in comparison to Best Wishes?
BW:
Ash's eyes (and overall design) get updated to Ken's Sugimori's current artwork
and are visibly brown from now on.
Ash's eye models are designed/animated "from scratch" from here on out in every episode.
XY:
OLM finds Ash's previous eye design from OS - DP,
uses them on the model for XY Ash, convert his OS-DP eye design
to match the BW better (as opposed from drawing them from scratch),
then stretch out his "black eyes" just slightly to add in the brown coloring again.
In a nutshell:
BW:
Eyes are totally redesigned.
XY:
Ash's black eyes are simply edited to be brown
with slight width added to them.