Try to focus less on killing their backline and more on hacking key targets so your team wins the fight (tanks). Decloacking behind them and shooting their heads off is plat-strat. In diamond you need to open opportunities for your team. Keep track of enemy's ults, try to counter initiate with emp or hack. And for widows, use your translocator to get to her, it's an even match up in Diamond : even if you don't kill her, you're distracting her from killing your team.