Since 2018, our starters have not matched the 5.4 IP/GS that rotation gave us on the phenominal 2018 championship team, but it has hovered at 5.0 IP/GS every year, except 2020.
IP/GS
5.0 2019
4.1 2020
5.0 2021
5.0 2022
The comparative strength of the rotation vs the pen has not been so consistent, and I guess it depends on what stats or eye test you are using.
Starters vs Relievers by Rankings in fWAR, ERA-, WHIP, and FIP
2018
SP: 8, 4, 6, 8
RP: 13, 3, 12, 6
2019
SP: 13, 16, 20, 12
RP: 5, 10, 19, 8
2020: N/A
2021
SP: 6, 12, 25, 6
RP: 9, 6, 23, 10
2022 (looks like both SP & RP dropped, but SP'er by more from '21)
SP: 16, 20, 20, 19
RP: 16, 26, 20, 15
Big change here from 2018 but not much from '19 & '20:
Save%/IR scored %
70%/32% 2018
52%/30% 2019
64%/31% 2021
54%/36% 2022