Apart from 157 to 1, I think it's more relevant that if your report is approximately accurate all that's left in the hex is about 100 troops and 35 guns, about 5-10% of the original unit. And with 90% losses (in just 3 days of combat, if I understand correctly) still they didn't retire nor surrender. This looks unlikely.
Also note that all his losses are destroyed devices, no disablements, this is unusual and might be a bug hint:
ORIGINAL: seydlitz
Defending force 1738 troops, 103 guns, 0 vehicles, Assault Value = 19
Allied ground losses:
1649 casualties reported
Squads: 68 destroyed, 0 disabled
Non Combat: 214 destroyed, 0 disabled
Engineers: 20 destroyed, 0 disabled
Guns lost 71 (71 destroyed, 0 disabled)
This looks quite suspect.
I wonder if all that's left in the unit are any static devices, and everything else surrendered this turn (thus the destroyed units).
I think you should ask the devs if this is WAD on the support or feedback forums, and/or ask your opponent if he saw anything strange on his side of the FOW.