The "pampered in ST" thesis is grossly exaggerated. ERod pitched a regular ST this year and his ERA is higher than last year when he had no ST, which I would interpret as maximum pampering.
Price was also pampered in ST this year, but his ERA is down from 2018, thus again suggesting that pampering is good.
Porcello pitched just 12 innings this year vs. 16 in 2018, which to me ain't that big a deal. But no question he is having a bad year, ERA 5.37 vs. 4.28 last year.
Sale threw 6 innings this year vs. 15 last year, and no question his ERA has shot up from 2.11 last year to 4.27 this year. However, we also know that he flat ran out of gas last year and in 2017 with great numbers thru June-July and lousy numbers afterward. Plus, as Cora said, everyone pitched extra last year while winning the ALDS, ALCS, and WS--a total of 14 additional games and 26 additional innings for Price, 15, for Porcello, 15 for Sale, and 10 for ERod. We also know for a fact that Sale's fast ball isn't as fast as last year, which I seriously doubt can be charged to a truncated ST.
No question, however, that our rotation is been at best inconsistent and way too much like Forest Gump's box of chocolates. At the same time it's worth noting that John Henry is paying Price, Sale, Porcello, ERod, and Eovaldi a combined total of $88M this year. Caveat Emptor.