Buyback yield uses net repurchases, so it subtracts shares issued for rsu grants and acquisitions. A company that spent $2B on buybacks and issued $1.6B of stock has a net yield close to zero, whatever the press release said.
Combined with dividend-yield it gives shareholder-yield, a fuller picture of cash returned. Unlike a dividend, a buyback carries no commitment and is typically cut first when cash gets tight.
Example: a $20B company repurchases $1.5B of stock and issues $300M to employees. Net is $1.2B, a 6% buyback yield. With a 2% dividend yield, shareholder yield is 8%.
Related: share-buyback, shareholder-yield, dividend-yield, stock-based-compensation