@contrarian23, thanks for the response, BTW. Your critique of my question was on point. Sorry to drop that post and then disappear. Some life happened, and I wasn't able to get back into the forums until the past couple of days.

To my OP, something just seemed "off", and my question was an "am I missing something obvious" flyer before I bothered to spend some real effort analyzing it. With that previous team, yes, I eventually got Sparky to start subbing and racked up a lot of pinch hits, but it was by just leaving the Pinch Hit and Double Switch settings pegged at five all of the time. I was hoping to be able to use those dials more tactically, moving them between 3 and 5. When that new season started, yes, it was only six games, but I felt as if I must not have learned anything the previous season, as, even with my settings on 5, Sparky was failing to make what seemed like obvious substitutions.

Though I didn't make it back into the forums, I did keep tinkering with the dials and eventually found (anecdotally) that my pitcher advanced settings were likely competing. It appeared that perhaps my TPC/MPC counts were too commonly generating lots of partial innings from my pitchers, thus leaving them too far from their TPC/MPC values when we were at bat for Sparky to be comfortable yanking them yet.