Tesio's idea of extemely fast race mares expending their "nervous energy" on racing and not passing it along to their offspring. The great race mares required time to rest back up to restore this "reserve" to be able to pass along their vitality to their offspring. How does this relate to Holland Lops you ask? There have been many great show does kept far too long on the show table, then promptly thrown into production, not resting on their shavings laurels. The results often times are either misses, reabsorbed or scattered litters or disappointing offspring. Perhaps, she too has no vitality to pass along to her kits?
All is not lost. Her offspring may turn out to be mediocre rabbits that place in the middle of the pack, all the while exhibiting no major faults. They have no outstanding trait to set them apart and put them in the number one hole. Yet when bred to a 1/2 brother or 1/2 sister or grandparent result in another nice show rabbit. This gives validation to the idea of quality skipping a generation which is an impetus to our line breeding programs.
Someimes a great Holland will seem to be a "pinnacle" rabbit. Some Top Lop, National and Convention Best of Breed winners have been a "pinnacle" rabbit. How many have ever produced a successive National or Convention breed winner or even class winner? Everyone chases after a son or daughter out of the illustrious winner like it were a Magic Pill for their own herd improvement. Most likely the quality has "peaked" and will not repeat within that line or for several generations of related animals Successive generations can only reach a certain limit. What do you do then? You need to breed that "pinnacle" animal into another line to create your own hybrid great animal.
If only it were as easy as identifying and isolating that one dominant trait that would allow us to consistently produce only awesome Holland Lops. Think cloning. But no, we are "stuck" with the laws of chance.
Now about those older brooddoes....Take heart and think of the great racehorse, Secretariat. His mother was 18 years old when he was foaled, about the equivalent of a 4 year old doe. The same could happen in your own rabbitry, any litter, any time. They're at the head of the stretch... so keep on trying!