There are a few ways we can tweak this. All of the examples below use internal testing query parameters, i can't suggest using these as part of normal production usage outside of A/B testing, but they work well for exploring variations
'opening text no boost links': '?search=morelike:%s&cirrusBoostLinks=no&cirrusMltUseFields=yes&cirrusMltFields=opening_text',
'opening text': '?search=morelike:%s&cirrusMltUseFields=yes&cirrusMltFields=opening_text',
'no boost links': '?search=morelike:%s&cirrusBoostLinks=no',
'basic': '?search=morelike:%s',
A_Summer_Bird-Cage:
basic
I Know Why the Caged Bird Sings
Princess Louise, Duchess of Argyll
J. K. Rowling
opening text
I Know Why the Caged Bird Sings
Themes in Maya Angelou's autobiographies
Abnormal behaviour of birds in captivity
opening text no boost links
Themes in Maya Angelou's autobiographies
Get Sexy
I Know Why the Caged Bird Sings
no boost links
I Know Why the Caged Bird Sings
Jerusalem the Golden
Princess Louise, Duchess of Argyll
Isabel_Fonseca:
basic
Emma Goldman
Martin Amis
J. K. Rowling
opening text
I Know Why the Caged Bird Sings
Kate Millett
Hillary Clinton
opening text no boost links
I Know Why the Caged Bird Sings
Mary Beth Keane
Elizabeth F. Ellet
no boost links
Martin Amis
Margaret Fuller
Emma Goldman
Andrew_Michael_Hurley:
basic
J. K. Rowling
Enid Blyton
Ernest Shackleton
opening text
List of James Bond novels and short stories
Harry Potter
James Bond
opening text no boost links
List of James Bond novels and short stories
Childhood's End
Deborah Swift
no boost links
Pure (Miller novel)
The Other Hand
Stella Gibbons
The_Queen_of_the_Tearling:
basic
Emma Watson
J. K. Rowling
Emma Goldman
opening text
The Sun Also Rises
The Twilight Saga
The Historian
opening text no boost links
List of Buffyverse novels
Witz (novel)
It's very hard to pick and choose a few small samples of queries and say "this is now better". I highly suggest, at a minimum, A/B testing variations and basing results on user click through and bounce rates. Back testing thousands of user queries and comparing them to user click through or satisfaction (clickthrough + dwell) might be much more useful.