SIRES OVER BROODMARE SIRES ARE VERY RARELY A NICK AND THEN THEY MUST HAVE EXTRA COMING THROUGH OTHER PARTS OF THE PEDIGREE TO RISE TO THE TOP. and there are some that pedigree analysts that have written about for years  like the Northern Dancer/ Mr Prospector nick, yet this only works 7% of the time so what about the other 93%, these are not very good odds at all. Looking at some that have been mentioned by numerous writers over the years are;

This cross was done only 39 times for 8 group one winners, 20% G1 winners to foals which are fantastically high, they were. Green Street, Our Unicorn, Helene Vitality, Jezzabeel, Grand Echezeaux, Hades , My Royal Captain and Provocative plus a group 3 and a listed winner.that 25% s/w to named foals. 
 Zabeels bottom line goes to the mare Diseuse and Vice Regal’s dam sire Le Filou is out of a daughter of Diseuse, To analyze these group one winners under my learnings. With the 5Th dam of Zabeel being by Vatellor out of Diseuse and Le Filou also by Vatellor out of a daughter of Diseuse this is a sister to the 3/4 brother.
Then you get Man’O’ War 7F x 6M for a colts breeding and Solario 7F x 7F for a filly’s breeding in this cross also.  However in Green Street and Our Unicorn both these geldings have Panorama in the bottom half of the dam's pedigree which gives line-breeding to Sir Cosmo 6F x 7M the other 3 Geldings Helene Vitality and Hades gives 2 sons of Solario to balance the 2 Daughters in the Zabeel x Vice Regal cross and My Royal Captain gives balanced line-breeding to Round Table. Then the 2 mares Jezzabeel has the sister Monarchy in her dams bottom half of the pedigree to balance the full brother Round Table that’s in Zabeel and last but not least Grand Echezeaux carries the mare Tara through a daughter in her bottom half of her pedigree to match the Tara coming through the son Norseman 4th dam sire of Zabeel.

This mating has been done 30 times, but as the 3/4 cross of Vatellor / Diseuse   However on this occasion there are 2 group one winners Booming and  Sound Proposition, this is because Booming is out of a mare by Grosvenor and Sound Proposition is out of a mare by a son of Grosvenor , who carries another daughter of Le Filou and this makes the statement you may have heard, Quantity overcomes distance, mind you it is working maybe not to the same extent but it does have a further 2 x G.2 and 3 x G.3 for a good 23% Group winners to starters.


I found this in print so I thought It needs a reply with my thoughts.
Leading First Season Sire Pierro has already proven himself with Danehill line mares – his Group 3 winner TULIP is out of a Rock of Gibraltar mare and is set to take her place in this year’s Golden Slipper. The Lonhro/Danehill cross is one of the most successful crosses on record with a staggering 7% Stakes winners to runners and over 77% winners to runners!
Here are my findings, in his first season at stud he covered 199 mares that produced 144 live foals. With only 8 winners he was able to claim the Champion first season sire, the following year he had 154 foals taking his tally to 298 of which 72 are winners of 120 races at the end of July 2018, which is approx 1 in every 4 at the moment. 
Here is an analyst of his best ones,
Pinot, his G1 winning filly, second dam by Danehill, this is what I wrote when she won the Oaks, Pinot has a double of Zabeel there are 34 runners that have this and she is the only stakes winner, but it has a gap in generations so it normally has no effect, however on this occasion as Pierro carries the son and daughter of Special the Zabeel does contribute by bringing another son of Special through. This pedigree also has line breeding to 2 daughters of Princequillo behind Mill Reef and an independent line with Somethingroyal plus 2 daughters of Buckpasser, plus the full sister Tessa Gillian refer dam line of Octagonal and the full brother Royal Charger who appears twice as the sire of Turn-To.
Levendi, G.1 winning Colt, his damsire Redoute’s Choice, this pedigree shows me that it also has
Knights Romance on the powerful dam line is a son of Royal Charger which is balanced by the sister Tessa Gillian in Pierro.

Tulip, G.2 winner her grandsire is by Danehill but also has Royal Charger in the pedigree of the doubled-up Sir Ivor to balance the sister Tessa Gillian.
G.2 winner His dam sire is also Redoute's Choice by Danehill also has in the pedigree  linebreeding to Sir Ivor 6M x 6F and Relic 6M x 7F,7F
Perata, G.3 winner, the dam sire Flying Spur by Danehill also has line-breeding 4M x 3F to Zabeel also Sir Ivor 6M x 5F, 5M  Forli 6M x 6F Northern Dancer 5Mx 5M,6F,6M and Native Dancer 7M,7F x 7F,7F, 6M.
Roy Had Enough,  listed winner, the second dam is by Danehill but also has, Sir Ivor 6M x 5F Nasrullah 7M,7M x 7M, 7M, 7F Hail To Reason 7M x 7F Princequillo 7F x7M Bold Ruler 7F x 6M  and balanced Native Dancers.
Kentucky Breeze, Listed winner also dam by Redoute's Choice, also has Round Table 7F x 7M Relic 6M x 7F, which shows up in Redoute’s Choice this may be assisting but is not the answer and balanced Native Dancers.
Satin Slipper, Listed winner, the damsire Flying Spur by Danehill also has the very close relations, Octagonal by a son of Sir Tristram out of Eight Carat to the sire line and Kaapstad by Sir Tristram out of Eight Carat to the dam line.
To summarize Danehill appears in 58% of Pierro's progeny that have raced and  8 of his 9 stakes winners have Danehill , so the percentages are 7.0% for group winners and 9.41 % for stake-winners, these figures may improve or deteriorate over the next few years but one thing is for certain, I do not think the figures stake up at the moment to call Pierro/Danehill a successful cross plus as shown they all have other line-breeding that is contributing.