Its very simple.... The logic in game engine is based on team salaries= best team= best results. It has always been that way I'm sure I am about to be 1-2 until all star break. The two ahead just have a early lead..
You have the correlation off; better teams have better players, and better players often do have higher salaries, but higher salaries does not necessarily mean better players. The things that matter most are the skills and game shape - so if you're going to try to reduce it to anything, I'd look past salary and instead focus on DMI since that's at least reflective of skills as affected by the gameshape.