Did Robert Boyett "help" cause Happy Days' decline in quality?

Robert Boyett for those who don't know, joined the production staff around 1978-79. Before this, the bulk of the production (besides Garry Marshall of course) on Happy Days was handled by Thomas Miller and Edward Milkis. I thought about this after watching the Rowdy Reviewer's "TV Trash" retrospective on Joanie Loves Chachi.

http://rowdyc.com/tv-trash-joanie-loves-chachi/

Not that it matters in regards to Happy Days but as the newly christened Miller-Milkis-Boyett Productions, no show outside of Bosom Buddies lasted for more than a single season. And even Bosom Buddies itself, only got two. And while it's hard to truly blame Robert Boyett for whatever went wrong w/ Joanie Love Chachi, but bare in mind that Edward Milkis none the less, but bumped down to "Associate Producer" on that show.