Here's how history changes, during the KG era ...
2008 finals, clearly, Kobe ball loses and there's no needed game 4 comeback, nor the let up in game 5, as the C's handily beat the Lakers, 4-1. This is the best bench in the NBA and Pops uses every one of them well.
2009, yes, we beat the Magic and advance but lose to the Lakers 4-1, however, with a healthy KG/Powe, it's a full 7 games against the Lakers, no definitive winner as the Lakers have moved away from Kobe ball and is now a full team effort. I still think the Lakers can pull that one out, as Ariza/Odom were playing like there's no tomorrow.
2010 finals, we beat the Lakers in 6. Sorry, but the '10 Lakers were not the same team as the prior year. We start by winning game one and then, the Phil Jackson curse is waived. Six games in total.
2011, with Miami disposed of, the C's beat the Mavs in 7.
So there you have it, 3 titles in 4 years.
And why Pops couldn't do it with the Spurs in the west is that during that time period, they were highly dependent upon a healthy Ginobili, to be a Paul Pierce during Q4, a.k.a. sixth man closer. Well, Manu was injured more often than not (plus aging) and finally, the Spurs had grown additional talent, not to have to do that, these past couple of seasons, making 'em a much more versatile team. In contrast, under Doc, the C's seldom worked on their bench, despite having players who could shave the minutes from Pierce and Garnett.