Nick Bosa and Christian McCaffrey missing practice is a cause for concernBosa has missed four practices in a row with soreness. And while the defensive end's workout regimen is renowned, there's nevertheless a concern any setbacks could cut into the regular season. Still, the fact San Francisco recorded a league-low 20 sacks last season, largely without Bosa in the mix, is worrying if his injury issues linger. As for McCaffrey, the 49ers appeared to simply give him the day off in light of his tightness. At the same time, either player being banged up at this stage before even the preseason begins is a development fans don't want to see.