Racing Positions49ers defensive end Aaron Lynch leaves practice with apparent injury8YNick WagonerO-line, backup QB among positions to watch as 49ers open preseason8YNick Wagoner49ers rookie LB exits on stretcher after collision8YNick Wagoner49ers try to regroup after Donavin Newsom's scary injury8YNick Wagoner49ers' Ray-Ray Armstrong takes turn with starters at weakside LB8YNick WagonerBrian Hoyer has strong practice despite facing constant pressure8YNick Wagoner