Well a fairly mediocre GM could result in the best start in franchise history because we have a great coach who made something out of nothing and made the GM look ten times better than he actually is.
Do you remember who Cavs GM was when Lebron won them the championship in 2016? Or who Spurs GM is during all those years of their championships and playoff runs? Or who Lakers GM is when they won the titles three in a row?
Don't just automatically assume that simply because the team is doing great, everyone is doing great. Sometimes all it needs is brilliance of one particular player or one particular coach to covers everyone else's ***.