I noticed that pretty much every match's victory is dependent on people knowing when to use and manage their ults.
Unlike popular MLG games like CS/Halo/etc where every character has basically the same power and winners rely mostly on their skill and strat, Overwatch relies mainly on rock/paper/scissors and coordination to know when to blow your ults and sweep the area. It's no where near as deep as a FPS where everyone is essentially equal and the winners are the better players.
e.i. Doesn't take much skill to coordinate a Zarya and Hanzo/Pharah/Tracer/Reaper/Dva/etc ult combo and wipe out the other team and cap the point.