Really? The i5 is older than the A5. You all were gripping when the mini and the 13" rMBP came out. I believe it has the same dated i5.
You are confused here. "5" in A5 designates 5th generation. This number increases with every new generation of Apple processors. "5" in i5 has nothing to do with processor generations. Intel uses 3, 5, and 7 similarly to how BMW uses them. They indicate the place of the processor in the power scale. There are tons of versions of i5 models. In Pixel, Google uses the latest one.