I share your excitement over various aspects of the 2024 Sox team. I do not think your projection is unreasonable, at all.
The Gio-less rotation is highly suspect: I agree. While many have had stretches of good to great pitching for 16-24 starts, none have had a full season of solid pitching. I suppose one could argue almost all good pitchers have bad parts of every season, but your point is well taken. I will say that Pivetta has had full seasons of looking okay.
2021-2022: 63 GS and a 4.54 ERA (4.35 FIP)- nothing to get excited about, but okay for a 4/5 slot pitcher. The problem is, he's our 2/3 SP'er, now. His best stretches were:
Last 2 GS or 2020: 1.80 ERA plus 15 GS to start 2021: 3.97 ERA
First 16 GS or 2022: 3.23 ERA and was at a 3.98 FIP after 25 GS.
Bello started 28 games, last year, which can be considered a full season, but a 4.24 ERA is not great. The 3.14 ERA after 15 GS and 5.58 the last 13 bolsters your point.
Houck has never started more than 21 games in MLB, and had a 5.01 ERA, when he did.
Whitlock has never gone beyond 79 IP or 10 GS in MLB.
Serious concerns, for sure.