49ers’ Colton McKivitz shrugs off critics, keeps coming back for more

SANTA CLARA — Colton McKivitz is like one of those inflatable punching bags that springs back at his aggressor. The harder you it it, the faster it comes back.

McKivitz, the 49ers starting right tackle, has taken his share of punches. He got left one-on-one too many times against Pittsburgh’s T.J. Watt a year ago and the result was three sacks. He’s taken shots in the form of grades from analytics services like Pro Football Focus, McKivitz gets blindsided from fans on social media, all...