In the San Francisco 49ers’ 11-on-11 sessions at training camp this week there is a lot of iron sharpening iron, especially on the line. Trent Williams, entering his 15th year in the league and sixth with the Niners, remains one of the best left tackles in the NFL. Not only has he gone against a premier pass rusher in Nick Bosa over the last few years, Williams is tasked with facing another fierce edge in rookie Mykel Williams.