5 burning-hot storylines 49ers will face in training camp

49ers training camp question No. 2: Will the offensive line be a massive problem?

Of all the position units on the Niners roster, perhaps even more than quarterback, few draw as much concern as the offensive line.

San Francisco was forced to switch out 40 percent of its Week 1 starting cast from a year ago, losing Pro Bowl left guard Laken Tomlinson to free agency before watching fellow Pro Bowl center Alex Mack retire just after OTAs.

Sure, the 49ers invested two 2022 NFL Draft picks to reinforce the depth, grabbing interior linemen Spencer Burford and Nick Zakelj on day three. Yet neither seems poised to be a plug-and-play replacement for either Tomlinson or Mack.

Instead, the Niners are likely to turn to second-year pro Aaron Banks at left guard, while hoping journeyman backup center Jake Brendel can adequately replace Mack.

Those are two shaky storylines to watch, and it’s possible the interior of the O-line winds up being a major liability for Kyle Shanahan and Co., which isn’t exactly the best thing San Francisco wants as it looks to implement Trey Lance as a full-time starter.