Take this with a grain of salt. This is my noobish understanding of OOTP!!
The way I play is, I picked a team (1981 Yankees) and I am GM/Manager. I even took over control of the minor league teams because I saw the AI made a couple of moves I didn't like at all. From opening day in 1981 and onward, all of my players, both pro & minor leagues, are going to develop organically. My influences will be how often do I play them? Am I forcing them into playing positions unsuited for them? Is my batting lineup setup to ensure RBI chances for my power guys? How am I developing that hot new prospect, Don Mattingly? Did I call him up too early?
All of that stuff is going to influence a player's current & potential ratings. The other way to play would be to pick a team (1981 Yankees), play as GM/Manager and pay attention to those things I listed above. One big difference, as far as I understand it, is every year my roster is going to get recalculated based on their real-life stats. So, if Mattingly stinks in 1983 on my team, his skills for 1984 will be influenced based on how he really played in real life. I don't think that means if he's batting .200 for me, he'll suddenly hit .343 as he did in 1984, but I think his potential would probably still show very good possibilities.
Again, please verify this with other people because I may be way off base and I don't want to destroy your saved game. Ahhh, I just called a friend. He told me to go look in League Settings > History and there will be options on the right-side to decide on which way you want to go.
After all that rambling, my answer would be "Yes! Your decisions will impact those pitchers' success and longevity. I've put pitch counts on some of my rookies or limited their innings." You don't want to baby them, but you don't want to have their arms blow up either. I also think the way I play would impact them more significantly over the long term than having ratings re-calculated every season.
I think.
