Where did I say signing starters was a sure bet?
I just inferred they were less hit or miss than RP'ers.
The Sox examples are not indicative of MLB, as a whole, and counting just free agents, like I think the debate was referencing, discounts the Beckett, Pedro, Porcello and many other extensions, but here are our biggest FA pitching singings:
Eovaldi -Good
Price- Not so good, but some argue otherwise
Lackey- Pretty good
Dempster- Many thought it worked out fine
Clement- disaster
If you want to count Paxton, Richards & Masterson, then is skews downward.
Look, lots of SP'ers flopped or got hurt, too, but I think significantly more did better than top FA RP'ers did over the last 4-6 years.