Reality check, we won championships in 2013 and 2018, if you characterize those years as failures, you're swinging way on the opposite side of homerism to straight out blind hate and disregard.
The Red Sox is not a 'dynasty' right now, but they do need to make a lot of moves to right the ship.
I'd count this year as a rebuilding year. Bloom needs to clear dead weight and put us in a position where we can compete in the future, say starting in 2020 if he can make the right cap clearing moves now and say restock the farm with some talent, I'd say that would be a successful step in the right direction.
As for Price, yes 18m value as a capable starting pitcher in today's market seems about right. The question comes down to what makes up for his 12m of extra salary per year. How much of that 12m value would you have to eat to send him away. Say 6m per year to a team that is desperate for solid starting pitching?
As for replacements, the only cost effective way is promoting from within. Free agents would eat into the potential cap relief unless you are going for strictly 1 year deals.
PS With free agency throwing crazy dollars at people, Price's value actually might be higher than we think, since signing replacement value pitchers is more expensive than ever in today's free agent market.