Fairly regularly? You almost never see obstruction calls made at home. Maybe like one per year in the league.
That’s the problem though, the inconsistency. Catchers technically violate the rule all the time but obstruction is barely ever called.
Watching the play now, i’d guess the issue was that Sanchez was straddling the line in front of home plate way before the throw came in. Whit wasn’t given a lane to slide as he was coming down the line. Knee coming down to block seems legal to me, the illegal part is the setup before the throw came
Haven’t seen the play yet, but going off this picture it seems totally legal. You see catchers move into the line all the time AS they are catching the ball. Depends how he was set up before the throw came in though. Whatev, its done and we won that’s what matters!