I now have Borg's numbers in all his Wimbledon finals.
1976 vs Nastase, Borg made his first serve on 10 of 12 break points
1977 vs Connors, on 12 of 14
1978 vs Connors, on 4 of 7
1979 vs Tanner, on 7 of 9
1980 vs McEnroe, on 12 of 13
The numbers for 1977 and 1980 are the best, and those were his five-setters against his two great rivals.
In '77 he avoided falling behind a set and a break by saving 4 break points in one game, making big first serves on all 4 and drawing 3 service winners/aces.
In '80 he prevented McEnroe from serving for a two-set lead by saving 3 break points with 3 service winners.
Borg's clutchness on break points may have been one of the key reasons that he was able to win 5 Wimbledons in a row.
He had poorer numbers in the '81 final, in which McEnroe finally beat him. In that match Borg faced 15 break points and made his first serve on, at most, 10 of them, probably a little less than that.
And poorer than all of these were his numbers in his USO finals:
1976 vs Connors, made his first serve on 10 of 15 break points (note, this year was on clay and Borg was rolling his serve a lot)
1980 vs McEnroe, on 3 of 13
1981 vs McEnroe, on 5 of 13