Below I have compiled what seem to me the most relevant numbers on which to judge and compare their respective careers. The fact that they were clearly contemporaries (10 months apart) and that their careers overlap almost entirely (1977-1992 vs 1978-1994) makes the comparison relevant. I find that it is much more difficult to compare Connors with either of them for example.
GRAND SLAM PERFORMANCE
GS wins: McEnroe 7, Lendl 8
McEnroe: 3 W, 4 USO
Lendl: 2 AO, 3 FO, 3 USO
GS Runner-Up Appearances: McEnroe 3, Lendl 11
McEnroe: 1 FO, 1 W, 1 USO
Lendl: 2 AO, 2 FO, 2 W, 5 USO
GS Semifinal Appearances: McEnroe 8, Lendl 9
McEnroe: 1 AO, 1 FO, 3 W, 3 USO
Lendl: 3 AO, 5 W, 1 USO
===============
CAREER TITLES (recognized by the ATP)
McEnroe: 76
Lendl: 94
CAREER TITLES (including those not recognized by the ATP)
McEnroe: 88
Lendl: 144
DAVIS CUP TITLES
McEnroe 4, Lendl 1
Two important caveats in this category:
1. Davis Cup is a team competition, not an individual competition.
2. Lendl was unable to play Davis Cup for the best part of his career. He was expelled from his country's DC team in 1983, and he was not allowed to play for any other country.
MATCH WINNING PERCENTAGE (this is so close it can be considered a tie)
McEnroe: 0.817
Lendl: 0.818
NUMBER OF WEEKS AS #1
McEnroe: 170
Lendl: 270
HEAD TO HEAD RECORD
McEnroe 15, Lendl 21
=================
There are other figures that could be brought up, such Lendl’s run of 18 straight finals in 1981-82, or his 44 match winning streak (second best) or his 66 match winning streak indoors. Also, Lendl’s level of dominance during his 5 strongest years (82, 85, 86, 87 and 89) exceeds McEnroe’s on any year except his best two (83-84).
The main argument you hear for McEnroe is that his 7 GS wins are stronger than Lendl’s 8. To this, one can argue that Lendl’s 2 AO titles in 89 and 90 were won at a time when the Australian was clearly a grand slam, and were won against very strong fields with all the top players participating; that winning 3 out of 4 different slams is better than 2 out of 4, and that his ability as an all-surface player comes out stronger on Lendl's record.. By the time you include runner-up and semifinal appearances, the GS performance difference is pretty substantial. The remaining relevant categories (career titles, number of weeks as #1, winning percentage and head-to-head record are, as a whole, overwhelmingly in Lendl’s favor.
And this is why I do not see any objective, dispassionate way to look at their respective records and fail to reach the conclusion that Lendl’s is significantly better. I also believe that if they had ended up with each other’s record (while retaining their respective personalities and media treatment) this kind of discussion would probably not even arise.
GRAND SLAM PERFORMANCE
GS wins: McEnroe 7, Lendl 8
McEnroe: 3 W, 4 USO
Lendl: 2 AO, 3 FO, 3 USO
GS Runner-Up Appearances: McEnroe 3, Lendl 11
McEnroe: 1 FO, 1 W, 1 USO
Lendl: 2 AO, 2 FO, 2 W, 5 USO
GS Semifinal Appearances: McEnroe 8, Lendl 9
McEnroe: 1 AO, 1 FO, 3 W, 3 USO
Lendl: 3 AO, 5 W, 1 USO
===============
CAREER TITLES (recognized by the ATP)
McEnroe: 76
Lendl: 94
CAREER TITLES (including those not recognized by the ATP)
McEnroe: 88
Lendl: 144
DAVIS CUP TITLES
McEnroe 4, Lendl 1
Two important caveats in this category:
1. Davis Cup is a team competition, not an individual competition.
2. Lendl was unable to play Davis Cup for the best part of his career. He was expelled from his country's DC team in 1983, and he was not allowed to play for any other country.
MATCH WINNING PERCENTAGE (this is so close it can be considered a tie)
McEnroe: 0.817
Lendl: 0.818
NUMBER OF WEEKS AS #1
McEnroe: 170
Lendl: 270
HEAD TO HEAD RECORD
McEnroe 15, Lendl 21
=================
There are other figures that could be brought up, such Lendl’s run of 18 straight finals in 1981-82, or his 44 match winning streak (second best) or his 66 match winning streak indoors. Also, Lendl’s level of dominance during his 5 strongest years (82, 85, 86, 87 and 89) exceeds McEnroe’s on any year except his best two (83-84).
The main argument you hear for McEnroe is that his 7 GS wins are stronger than Lendl’s 8. To this, one can argue that Lendl’s 2 AO titles in 89 and 90 were won at a time when the Australian was clearly a grand slam, and were won against very strong fields with all the top players participating; that winning 3 out of 4 different slams is better than 2 out of 4, and that his ability as an all-surface player comes out stronger on Lendl's record.. By the time you include runner-up and semifinal appearances, the GS performance difference is pretty substantial. The remaining relevant categories (career titles, number of weeks as #1, winning percentage and head-to-head record are, as a whole, overwhelmingly in Lendl’s favor.
And this is why I do not see any objective, dispassionate way to look at their respective records and fail to reach the conclusion that Lendl’s is significantly better. I also believe that if they had ended up with each other’s record (while retaining their respective personalities and media treatment) this kind of discussion would probably not even arise.