Another look at the Yankee starters not named Cole:
Kluber was a stud-no doubt, and not for a short time. He was one of baseball's most dominatnt pitchers from 2014 to 2018 9151 ERA+ 1.016 WHIP), but he's pitched less than 37 innings from 2019-2020. He looks to be getting back in form, but is still far from those 5 year numbers.
3.48 ERA (116 ERA+) 4.00 FIP
1.403 WHIP is a worrisome number.
His 4.1 BB/9 is over double his career number.
Even if you can put aside German's personal issues, and missed 2020 season, his numbers are not all that good from 2018 to 2021:
4.47 ERA (98 ERA+)
1.207 WHIP
2.7 BB/9 and 9.9 K/9 rates (1.8 HR/9)
He's doing much better, this year and was decent in 2019, but still...
Although Montgomery's FIP of 3.92 since 2019 is decent, his low BB/9 rate and good K/9 rate are about his only redeeming attribute.
5.02 ERA (84 ERA+)
1.249 WHIP
I've always liked Taillon, but he has not looked all that good, so far, this year:
5.40 ERA (75 ERA+) 4.48 FIP
1.200 WHIP is encouraging, but the 2.2 HR/9 hurts.
His K rate is way up, too (11.6).
All in all, I'm not sure any of the concerns from pre-season have been answered, although Kluber is showing nice signs, despite some troubling numbers.
No doubt, the Sox starters have been overachieving expectations, and one could show similar past troubling numbers on every Sox pitcher not named ERod, but so far, they keep chugging away and adding to their sample size of plus production, except for Eovaldi.