At the start of last year, I felt the pen was our weakest (not weak) link. JF managed the pen very well. We squeezed the best from some guys I had little hope in before the season started. With injuries to Smith, Thornburg, Ross and Workman, we ended up doing very well (4th best pen WAR). Remember, Ross has the 3rd most Sox RP'er IP from 2014-2016 and the 5th best pen WAR on the team.
The 2018 pen looks like it might be much better, especially if those who seemingly over performed last year can keep it up this year. Assuming good health and taking the optimistic view via some cherry-picking, here's how our pen could look:
Closer: Kimbrel has been one of baseball's best closers in MLB over a long period of time and arguably was the best last year.
RP2: Carson Smith had a 0.91 WHIP from 2014-2015 (15th best out of 165). He had the 15th best K/9 rate at 11.8. His ERA- was 54. Yes, it was just 78 IP, but that's not a tiny sample size.
RP3: Tyler Thornburg does not have a great history, but his 2016 season was pretty damn awesome. He had the 11th best RP'er WAR (2.0), 12th best WHIP (0.94), 7th best K/9 (12.1) and an ERA- of 56.
Joe Kelly gets pushed from 2 to 4.
Matt Barnes gets pushed from 3 to 5.
Workman returns. Hembree may continue to improve. Maddox could repeat 2017 but over a longer time. Scott looked pretty good.
I'm much more optimistic about this pen than I was this time last year.