Peak Red Sox CBC was 2003, right? That year, they had 10 different players earn saves. In total there was 36 saves and 21 blown saves.
Last year, there were only 5 (only Kimbrel had more than 1). In total there were 39 saves and 18 blown saves.
Seems to me that if the Sox had the 2003 bullpen last year, they should have had 3 additional losses. At 90 wins, the Sox would have hosted a WC game.
The 2003 relief corps had some solid arms too: Mendoza, Timlin, Embree, Williamson (coming off a solid 2002), Seanez, Lyon, etc. Most people thought the relievers would be good. There were enough arms there and an improvement from guys like Sauerbeck or Rupe could have really solidified the staff. The only question mark was the closer. At the beginning of the season, the CBC plan didn't work. "On May 29, Kim was traded to Boston for Shea Hillenbrand. Kim remained as a starter through June, but the Red Sox needed him as their closer because the Red Sox's closer-by-committee approach implemented following the advice of statistician and Red Sox adviser Bill James was failing." I remember a lot of TALK RADIO CALLERS worrying about Kim and how he handled himself on the mound in 2001 WS and worrying that he wouldn't be able to handle it. He was ok and had an 84 save %. In 2017, there were 8 relievers with over 10 saves that had worse save percentages.
What if the bullpen had a lockdown closer in 2003. What if they had simply re-signed their All Star 2002 closer Ugueth Urbina? Old friend Tom Gordon? Would that have put them over the top in 2003 and given Grady Little more confidence in the pen? WHAT WOULD THAT ALTERNATE TIMELINE LOOK LIKE?