Sadly for Doyle, he was about replacement level for the next two seasons and was out of baseball after the 1977 season. In December 1977, the Red Sox replaced Doyle with the very man who had replaced him in California: Jerry Remy. The Sox gave up pitcher Don Aase, who would have a couple of mediocre seasons starting for the Angels. However, he later became a very useful relief pitcher.
Remy never became a star, but that's mostly because of knee injuries he would suffer in the next few seasons. In the long run, the Sox probably missed having Aase, who actually had a nice little career. Still, Jerry was a fan favorite and useful player who has made quite a nice career for himself as the Sox color commentator.
So, there you have it. Remy displaced Doyle so that he could help the 1975 Red Sox. Then, Remy became the starting Red Sox second baseman after Doyle's departure. Interesting how that worked out.