Because if they were, no one would be mocking him on the interwebs for his extremely weak and bogus op ed on tennis challenges.
First, PK doesn't seem to know much about tennis:
The rules allow three incorrect challenges per player per set. In a best-of-five-sets match (which is normal for men), that means at least 18 available challenges per match, none of which carry over from set to set.In other words, use ’em or lose ’em. A player can get an additional challenge if the match goes into a tiebreaker, or if a fifth set goes overtime.
Best of 5 matches are played at the 4 major championships and in Davis Cup ties, meaning that they are an aberration, not the norm.
Second, he does not seem to know what the word substantial means:
And the rewards for challengers can be substantial. For example, the No. 10 seed at the Open, Fernando Verdasco of Spain, averaged 0.4 challenges per set and had a sparkling 43 percent success rate. If he challenged once per set, like Federer, and his challenge success rate fell to a similar 30 percent, it could mean one more point to him in a three-set match. If his success rate didn’t fall as much, however, and he challenged twice per set it might mean as many as three more points in a five-set match. Either way, it could be the difference between winning and losing.
Third, he seems to think that winning a challenge gives you the point (see the above quote). It does sometimes, but often winning a challenge just causes the point to be replayed.
Fourth and most importantly, he seems to forget that the status quo is neither player challenging much. If they both increased their challenges and were equally good at it, then there would be exactly zero net advantage to either player. In other words, in *equilibrium* challenging more cannot be a competitive advantage (not even a tiny one like what he cites in the quote above).
Aside from that, the piece was terrific!