fangraphs has the Yankee SP'ers ranked 3rd, too, but mostly on the strength of their depth. They are the only team with 7 pitchers over 1.1.
5.5 Cole
2.7 Kluber
2.1 Montgomery
1.9 Taillon
1.2 German
1.1 Garcia
1.9 Sevy
0.2 King
0.1 Schmidt
(I think Kluber & Montgomery are high, but maybe King & Schmidt are too low.)
Their top 4 (not counting Sevy) is 12.5/ Top 5 is 13.7
With Sevy: Top 4:12.5 / Top 5:14.1
Some teams below the Yanks:
NYM:
Top 4: 14.5 (deGrom, Stroman, Carrasco, Syndergaard, Walker)
Top 5: 15.7 (+Peterson)
Both better than NYY
WSH:
Top 4: 13.3 (Scherzer, Strasburg, Corbin, Letser 0.9)
Top 5: 14.2 (+Ross)
Both better than NYY
CIN:
Top 4: 10.7 (Castillo, Gray, Mahle, Miley)
Top 5: 11.7 (+Lorenzen
CWS:
Top 4: 11.2 (Giolito, Keuchel, Lynn, Cease
Top 5: 12.1 (+Rodon)
ATL:
Top 4: 9.9 (Morton, Fried, Soroka, Anderson)
Top 5: 11.3 (+Smyly)
The Sox are ranked 15th:
2.6 ERod
2.3 Sale
1.9 Eovaldi
1.4 Richards
1.3 Perez
0.7 Pivetta
0.5 Houck
0.3 Seabold
Top 4: 7.2
Top 5: 7.9