The Sam moves up to take on the run and to not give a free blocker access to the next level. In other words - support. Otherwise, the OL has the advantage on the strong side and you’ll get gashed. As far as the best way to defeat gap blocking/option, it’s also the best way to choke off any ground game - a toilet clogger of a DT that can regularly consume two blockers at the LOS and 5-techs that can hold the edge. Not a whole lot of room for a mobile QB to run if those gaps are closed. They can bounce it to the outside, but if the DL is doing their jobs, a free blocker won’t be able to get to the next level. This lets your LBs flow to contain the run and unless they take a piss poor angle, it usually results in minimal yards gained. Shelton has performed better than expected, but he isn’t what this defense needs to cure the issues against the run. That was on full display in this game. I don’t think I’m treading into hawt taek territory by pointing out that he was frequently giving up leverage and was getting handled one-on-one.