Right. It does
something to gameplay. Not sure, but you can tell. As for the subs, a bit further on detail. The game against the Ravens I played on 15 Minutes with 13 runoff (score was 40-38 could affect higher scoring games). Murray had 23 carries, Mathews had 3 carries, and they were all after Murray got hurt for 3 weeks and I was already passing heavily.
The game against the Bears I played earlier Mathews had 20 carries, Barner had 7 and it seemed as though Mathews would be in for 2-3 plays then Barner, Mathews for 2-3, Barner for maybe 2, Mathews back in. It was much more noticeable that subs were actually happening.