I agree with the post about hard-throwers being such a crapshoot, which is why I'm ok with the sox trading them away, knowing they can always afford developed talent.
Can they afford it though? With all the young guys in the system (Benitendi, Moncada, Boegarts, Betts, Bradley), your going to sacrifice one or more of them to pay for a pitcher. It's just the reality. And that's fine, but I'd rather them not waste potential ace arms (Espinosa, Kopech, Groome) for a middle-end of the rotation guy, which is basically what they get you these days. If your system has a consistent approach, they should constantly be pumping out guys who can fill that role. In reality, you'd hope between those 3 guys, one becomes an ace, one becomes a rotational piece, and one is probably a bust. But the fewer ping pong balls, the lesser chance of finding the ace and the greater chance of finding the bust.
It's interesting, but if you look at the WS teams over the past decade, their best pitcher during that time was probably drafted and developed, or at a minimum developed. For every team with a traded/FA piece (KC - Cueto and Shields; STL - Carpenter x2; NYY - Sabathia; Sox - Beckett) there are several more with home-grown (Mets - deGrom; SF - Bumgarner; Red Sox - Lester; Cardinals - Wainwright; Giants - Cain; Tigers - Verlander; Rangers - CJ Wilson; Giants - Cain; Rangers - Wilson; Phillies - Hamels x2; Rays - Shields; Rockies - Jeff Francis; Tigers - Verlander).
I know the Red Sox have had better starting pitching the past few weeks and even months, but the reality is that even though they've had a great stretch, the inefficiency of those pitchers early in the year can easily be to blame why the bullpen has been in such shambles. Overworked, tired, broken down. Part of that is also on the stupid manager, but some falls on the starters, bullpen never got a break.
Furthermore, spending on pitching is always a risky deal. Sox are spending $30+ million on Price and getting $10 million results. It's harder to find pitchers to meet results than hitters, especially given the risk of the deal. Even if you look at LAA, they offered Pujols a stupid contract. But even if you look at those numbers, he's averaging 25 HR's, 94 RBI's, hitting .264. Obviously this season is not over and Pujols is raking right now, but just shows that even later in his career (hes now 36 and signed at age 32), you can still find decent productivity even if the average drops. It's so rare that a pitcher comes even close to living up to their big free agent contract. If you're lucky you may get 2-3 good years before they fall off a cliff.