Because we have a more-Simmonsy guy in JRM than is Christian Jones. Yet its Jones that gets most of the snaps by far. This is because our HC values run stuffing ability at all front seven spots and rarely chooses to sacrifice that stoutness for speed/athleticism. JRM is clearly better in coverage than Jones, worse taking on blocks against the run, and more productive behind the LOS if he’s kept in space. Killebrew as well though even more Safety in your WLB/Safety hybrid player.
If we truly preferred a cover backer over another run defender at LB, we already own that option, yet never or rarely choose it. Late in the year when Jones was out, JRM played well IMO. The LB play got better once all the fat boys were on the bench hurting and the smaller faster backers were at those spots. But I expect that my view doesn’t matter to Patricia and when everyone is healthy again, we won’t be seeing much below 250 at any LB spot getting much run.