Here are the ones I think are truly contributing this season--Bregman, Anthony, Story, Gonzalez, Narvaez, Duran, Rafaela, Abreu, Ref--and Crochet, Chapman, Bello, Giolito, Chapman, Whitlock, Wilson (but not tonight), and Bernardino. That's 17 out of 26. I also think Wong contributes as an excellent backup catcher and despite his rotten OPS this season. His CERA is better than Narvaez's.
I would love to add Dobbins and Mayer, but they didn't play enough. Latecomer May has an ERA of 2.87 in 3 starts so far. Lowe is also a latecomer who just batted in the go ahead run with a double. His 3 game Sox OPS is well over 1.000.
So, if you give me May and Love to add to my list because both look awfully good so far, that's 19 total