He is and was a useful part, but not someone who is all that hard to replace.
We have a lot of iffy pitchers that could have a better year than 3.87 or 4.39.
Thornburg might offer the best hope.
A whole year from Brasier could help, if he can repeat 2018 or even come close for the full season, we'd see a big gain there.
Barnes really came into his own last year. Can he take a step back? Of course, but so can Kimbrel, Ottavino and Britton.
Hembree and Workman are probably long shots, but if you go by your stat, ERA, there's a good chance at least one can come in between 3.90 and 4.40. Hembree's career ERA is better than Kelly's (3.46), and his 4.20 ERA in 2018 was better than Kelly's. He also did well in the playoffs. in the 81 IP Workman has gone over the last 2 years, his ERA is 3.22. His 4.38 career ERA was better than Kelly's 2018 ERA. These numbers show some hope.
Velazquez had a 3.18 ERA last year in a pretty large sample size of 85 IP, and Johnson's was 4.17 in 99 IP)- both better than Kelly's 2018 ERA. If just one can repeat or improve, we'll have someone (or two) who can pitch 2 innings at a time every few games.
Wright's injury is a big question, but his numbers blow away Kelly. His 3.69 ERA from 2016-2018 was brought down by his 2017 partial season plagued with injuries, but he's a good hope, if he stays healthy.
Carson Smith, Poyner, Lakins, Walden, Feltman and our resent signees all offer long shot hopes, but the sheer number of hopeful pitchers increases the odds that just the 2-3 we need can come through. Of course, the big risk is we burn a few games finding the best 2-3, and finish in second place by a game or two. Certainly, that's a risk. That being said, I like our top 8-9 RP'ers enough to think we will not need to spend a long time going through our options to find the best 7.
Most teams use 9-11 RP'er pretty significantly.Last year, we had 8 guys with 33+ IP and 12 guys with over 20 IP. Kelly led all RP'ers in IP with 65.2.Here's the list: (RED= no longer with the Sox)
65.2 Kelly 4.39
62.1 C K 2.74
61.2 Barnes 3.65
60.0 Hembree 4.20
54.2 Velazquez 2.63 (Maybe he can add 30-40 IP in relief.)
41.1 Workman 3.27 (Maybe he can add 10-25 IP.)
38.2 Johnson 4.19 (If he doesn't have to start much, he could add 35-50 more relief IP.)
33.2 Brasier 1.60 (He's the big wild card. He could suck, of he could gives us 30 more IP.)
29.2 Wright 1.52 (Another wild card with huge upside potential to add IP and help.)
24.0 Thornburg 5.63 (More huge upside potential)
22.2 Pomeranz 5.56 (Addition by subtraction/ his numbers help offset the good numbers lost.)
15.0 Cuevas 7.20 (More addition by subtraction)
14.1 C Smith 3.77 (A long shot hope & prayer)
7.2 Haley 4.70
6.2 Scott 8.10
2.1 J Beeks 11.57
(ERod 6.1/4.26 & Eovaldi 3.2/ 4.91)
Total numbers for RP'ers who are no longer with us:
ER/IP
32/65.2 Kelly
19/62.1 Kimbrel
14/22.2 Pomeranz (RP only)
12/15.0 Cuevas
4/ 7.2 Haley
6/ 6.2 Scott
3/ 2.1 Beeks (RP only)
90/182.1
4.47 ERA Total
Take away Kimbrel's numbers:
71 ER in 120 IP (That's a lot of IP to be improved upon!)
5.33 TOTAL
Replacing Kimbrel is not going to be easy. Replacing the others should not be hard at all.