This so much. Just because she doesn't have to pull the variety out to beat players doesn't mean she doesn't have it.
This match shows her tennis IQ >>>>
Her placement and disguise on her serve (as always) to set up the v-plays, her slices, using topspin-heavy shots to work Henin off the court and give her no pace, the wrong-footing.
Part of her tennis IQ is that she knows she doesn't need to use it to win, so only uses it when it's needed. In this sense, she has one of the best shot-selections on tour.
So much this !! I was thinking of that exact match as well.
I don't know why people disliked it, despite the heartbreaking ending, I loved it. Sure it was not spectacular (minus the end of the second set that was all vintage Justine) , but very tactical. I thought it was a nice change from the usual ballbashing game we could see in most of WTA matches.
And in my opinion, that's what characterized their matches.
Henin did a major tactical mistake : the way she attacked Serena's second serve. IMO that cost her the match (or we could say Serena's seconde serve tactics won her the match), she was too aggressive on those, she wanted to take the early advantage in that rallye. That was not a good move, because at the beginning it was already a flop, and I don't know why but she kept playing that tactic. Moby
was saying how stubborn Justine could be , especially in relation to her tactics during a match.
Anyway, to answer the question, I really don't know. More than talking about who has the highest tennis IQ, I prefer to talk about the tennis IQ of players
because well, I guess Hingis is an obvious answer.
But anyway, I've never seen Evert/Graf play enough to notice a change in their tactics, depending on their opponent. I can't judge.
I agree that Serena is very underrated. I don't think you have to be smart all your career to prove you understand tennis, actually when she was younger, Serena had all her physical abilities, that fire and explositivity in her groundstrokes, and moved really well. But her serve was not as performant as it is today.
Now that she has gotten older, she changed a few things in order to last longer on the tour -- and I feel it's part to the tennis IQ as well.