Naturally, like in any job, there are some who are better than others. And, yes, some luck is involved too. But, I believe the biggest factor is: you are only as good as your players. As has been stated many times, Geno is great at recruiting NOT necessarily, the best players, but the best ones who FIT into his program.
Some of you remember Casey Stengel, who managed those great Yankee teams of the 1950's. .........THEN, he managed the early Met teams, filled with rookies and "Over the Hill" players.
The team set a Major League record for losses.....WHY?...The players on the rosters.