The absolute best value in players are those who are really talented and acquired when the team has several years of control, usually thru the farm system, but sometimes by trade.
If you go back to that crucial scene in the movie Moneyball, the one in which all those old scouts are shot down by Billy Beane and his new assistant, you are looking at a quick fix solution and not one teams should follow routinely. Yes, absolutely, get value and even use sabermetrics to help you in making trades, but young talent and especially evaluating young talent and bringing it along are crucial to any MLB team. Billy Beane, at least in the movie, says that all scouts are worthless, and he is wrong.
Relatedly, it's a truism in MLB that the big money comes from long-term contracts in which the biggest part of the salary comes at age 30 and after, which is when players wear down, lose their timing, get injured, whatever. Consider the following data on the 2021 Sox players--by name, age, salary, and WAR--
Sale, 32, $30M, WAR .1
Bogaerts, 28, $20M, WAR 3.9
JDM, 33, $19M, WAR 3.1
Eovaldi, 31, $17M, WAR 3.0
Price, 35, $16M, WAR 0.0
Pedroia, 37, $12M, WAR 0.0
Richards, 33, $8.5M, WAR .3
E. Rodriguez, 28, $8.3M, WAR .9
Ottavino, 35, $7.1M, WAR .8
Vazquez, 30, $6.2M, WAR .7
Devers, 24, $4.8M, WAR 4.0
Rike Hernandez, 29, $6M, WAR 3.8
Barnes, 31, $4.5M, WAR 1.2
Perez, 30, $4.5M, WAR .7
Renfroe, 29, $3.1M, WAR 1.8
Plawecki, 30, $1.6, WAR .1
Sawamura, 33, $1.2M, WAR .8
Verdugo, 25, $650K, WAR 1.9
Pivetta, 28, $610K, WAR 2.4
Dalbec, 26, $575K, WAR -.6
Whitlock, 25, $570K, WAR 2.3
Duran, 24, $570K, WAR -.4
If you further divide a player's salary by his WAR, you can see that the best Sox player values this year are under 30 years old--except for Sawamura.
Price is I think a great example of the folly of giving a long term contract circa age 30. And maybe Sale is too even though I like him a lot. JDM has actually produced and I think was the key bat added after 2017 who made a big difference in 2018. And Eovaldi and Barnes, both 31, are also pretty good value this year. I think the Bogaerts contract was/is a good value, but shudder at what Devers will want when he becomes a free agent. Think Mookie Betts.
About Pedroia's $12M. It looks bad, but 2007 (his rookie year) thru 2021 (including 4 years of basically not playing), 15 years, his total WAR was 52 and his total salary was $138M, so the Sox were basically paying him $2.65M/WAR, which is actually not bad. Jacoby Ellsbury also came up in 2007 and his final year was 2020. His cumulative WAR was 31 and total salary was $168M.