He already explained that the expectations are wrong to begin with.
2013 models had drives from different manufactures and some of those were slower than others.
Here's an example: Say 2013-A-SSD > 2013-B-SSD and we have the same two A and B SSDs in 2014 machines.
Then 2013-A-SSD > 2014-B-SSD.
With just one machine (and without knowing the specifics) you can deduce from the above that "2014 drives are slower than 2013s" when in fact they are the exact same 2 models that 2013 Air's had.
2013 models had drives from different manufactures and some of those were slower than others.
Here's an example: Say 2013-A-SSD > 2013-B-SSD and we have the same two A and B SSDs in 2014 machines.
Then 2013-A-SSD > 2014-B-SSD.
With just one machine (and without knowing the specifics) you can deduce from the above that "2014 drives are slower than 2013s" when in fact they are the exact same 2 models that 2013 Air's had.