Those are supposed to impress people?
Well, to be honest, they are quite dismal statistics for such a great player,
BUT:
Courier did not match well with Sampras or Becker as:
1. He had a strong forehand, and Sampras and Becker's forehands were only slightly weaker than Courier's (in his prime).
2. His backhand, though solid, was a huge weakness compared to Sampras and Becker's excellent backhands
3. His serve was not a big weapon compared to Sampras or Becker's huge serves
However compared to Agassi and Edberg (both over which he had winning head to head records against):
1. Courier's forehand was approximately equal to Agassi's and better than Edberg's.
2. Courier's backhand, although weaker than Agassi's had more margin for
error. Edberg's backhand was obviously better, but Edberg relied more on finesse and looking for the ball which he could attack, rather than consistency, which shows in their match ups.
3. Courier's serve was better than Agassi's and his serve had more pace than Edberg's.
In conclusion, Courier could not really match up with Sampras or Becker on the baseline, as both had better backhands, and he lacked in the serving department compared to both players.
However, against Agassi, Courier could match Agassi at the baseline, because he was more consistent, and this did not change until Agassi started getting more consistent (about 1994).
Against Edberg, he was the perfect matchup of the 4, because Edberg's groundstrokes were not hit as hard as the other 3, so Courier could outhit him. Charging the net constantly, Edberg just did not hit hard enough to give Courier any trouble, and did not put enough pace on his serve.
As a result, Courier managed to pin Edberg at the baseline, and basically beat him from there. If Edberg did come to the net, Courier's passing shots were good enough to finish him off, and Edberg's serve would become way to inconsistent (a classic example is the 1993 AO final).
That is why Courier's record is so good against Agassi and Edberg and so poor for Becker and Sampras.