Managers won't be surprised ... if they've read the 1981 book.
I think most people would be surprised to find negative correlation between individual ability and team ability, unless they've read this book or something like it. Weak correlation, perhaps, but outright negative correlation is truly surprising.
It's not clear to me that negative correlation was the finding. For example, the result does not show that teams of randomly selected high aptitude individuals perform worse than teams of randomly selected non-high aptitude individuals.
From what I can tell, the only finding here is that teams with individual aptitude as the sole selection criteria performed poorly in competition against teams that had more traditional selection process. This would be an expected result for me.
I don't even manage, I just watch team sports, and I know that you can put together star players and the team just falls apart. Sometimes also, when you cut an underperforming player your star player also spontaneously crashes in performance.
The same thing happens with rock bands. Sometimes they tried to put together bands called "supergroups" with star musicians from other highly-successful bands, and the results were usually underwhelming. It's probably because many times, one of the "underperforming" musicians does various other important tasks that don't involve technical ability on their instrument. One example here is Nikki Sixx from Motley Crue: he's a competent bassist for that type of music, but definitely no virtuoso, but his big contribution to his band was in songwriting, not bass playing, and his songwriting is arguably one of the big things that made the band so popular and successful in its time.
Also, sometimes certain people just work really well together, and one of them may not seem all that great on their own.
I think most people would be surprised to find negative correlation between individual ability and team ability, unless they've read this book or something like it. Weak correlation, perhaps, but outright negative correlation is truly surprising.