Well, to be fair, the average was 1:47.82 (thereabouts), right?
And here is a list of all those capable of that average or better. Jesse Garn and Joe McAsey are the only 2 of that 4 man group this indoor season who have open 800s beneath that record average. Any combo of the top 10 from the USATF's list should have been able to eclipse the recent record that was set with relative ease.
Besides just speculating as to how a group of better 800m runners would have done, it is also worth looking at how often relays like this are even run. I'm all for a strong effort since it's good for the sport and entertaining to a degree, but clearly this record wasn't sacred or nearly unachievable etc. Seems like there was very little on the line which doesn't do much to cause excitement.
800 METERS
1:45.10
1 Donavan Brazier Nike Feb 18 USATF Ind
1:45.53
3 Drew Windle Brooks Feb 03 Millrose G
1:46.49
1 Sam Ellison Boston AA Feb 10 Hemery Inv
1:46.57 3f2 Erik Sowinski Nike Feb 06 Düsseldorf
1:46.61
5 Clayton Murphy Nike Feb 03 Millrose G
1:46.99
2 Russell Dinkins New York AC Feb 10 Hemery Inv
1:47.37
1 Devin Dixon Texas A&M Feb 10 Tiger Paw
1:47.58
6 Jesse Garn Hoka
-NJNY Feb 03 Millrose G
1:47.63
5 Quamel Prince unat Feb 18 USATF Ind
1:47.74
2 Myles Marshall Harvard Feb 03 Lehane Inv
1:47.77
3 Joe McAsay Hoka
-NJNY Feb 03 Lehane Inv
1:47.79
1 Isaiah Harris Penn State Jan 27 National Inv
1:47.82
1 Thomas Staines Colorado State
-Pueblo Feb 03 Colorado Inv