This is how Bodo sized up an ATG in Courts of Babylon, speaking of Lendl:
Ultimately, Lendl would win eight Grand Slam titles, one more than his lifelong tormentor, John McEnroe, and the same number as his other major rival, Jimmy Connors. He would contest nineteen Grand Slam finals, appearing in the championship match in at least one of the Big Four tournaments for a solid decade beginning in 1981. Lendl led Czechoslovakia to a Davis Cup victory in 1980...
Lendl was ranked in the top ten for 13 consecutive years, a streak surpassed only by Connors (16 successive years). He won 94 sanctioned titles in his career, 17 more than McEnroe but 15 fewer than Connors. Between 1985 and 1988, Lendl held the world’s number one ranking for 157 consecutive weeks, second only to Connors’s 160-week run. But Lendl has spent the most total weeks in the number one position (270 weeks—2 weeks longer than Connors). Thus, he has a legitimate claim to being the top player of the Open era.
Judge Murray on that basis rather than merely how many slams he won.