Most franchises improve through hard work and good coaching.
Most franchises win championships through one way = getting good players anyway you can (trade, draft, FA)
The bottom line is your team and franchise needs the best player and in some cases 2 or 3 of the best players.
And if you don't have the right coach, the right GM to work with, etc, having great players/great talent still don't mean jack.
Look at the 2nd House Rockets championship, the Detroit Pistons or last year's Dallas Mavericks....they all needed some good fortune to go their way.