Whilst there were some truly great patrician generals and politicians in the Republic, Rome in Gaius Marius' day was becoming the province of the Novus homo - although he is the epitome of the man whose rose from provincial obscurity to the consulship, he was by no means unique in doing so. Nor were New Men necessarily better generals than patricians - note Gnaeus Mallius Maximus, whose loss at the Battle of Arausio (105 BC) was considered one of Rome's worst defeats since Cannae (216 BC).
Where the Romans triumphed was by learning from their mistakes. Cannae led to reforms within the army - abandoning the Greek models until then strictly followed, by dividing the phalanx into columns; appointing one commander, rather than alternating command during battles between the two consuls - which in turn led to Scipio Africanus' rout of Hannibal at Zama (202 BC). After Arausio and the many defeats of patrician-led Roman armies by the Cimbri and Teutones, SPQR decided to put Marius in charge; he dramatically reformed the army, and put an end to the menace of German hoards descending into Italy.
The Romans pulled victory from adversity, partly because that was when they were willing to ask 'outsiders' for help. Sometimes, when researching Marius, I loathe the old patricians with their petty snobbery and sense of entitlement - the way Metellus kept trying to put Marius down during the Jugurthine War.
Sir Lewis Bernstein Namier was writing about Georgian England, but this description of the 'type' is the best I've read, and suits patricians equally well:
old aristocratic houses or families ... can best be described as the aftermath of great men