Isn't the core of the answer to the Red Sox starting pitching ( vs. budget) the ultimate failure to draft and develop , within 3-4 years, starters capable of being a #2-#4 inning eater who is on a club controlled pre-arb/arb basis? Who was the last one , Buch/ Lester(?), maybe you can count Erod in a small stretch.
Better yet, who is the next one to come up through this system ? Whitlock was a NYY gift , much appreciated. Houck is a candidate if they can ever figure out which role he should be in , and if he can go more than 4 innings.
Don't strain yourself trying to figure out how they got to this position. Basically a 15-20 year failure to develop reliable arms .