"She's batting a thousand."
"She was aggressive, right out the gate."
"It's like batting practice."
"She did the one-two punch."
"She's waiting in the dugout."
"She's an effective counter-puncher."
"Think of her body as a race car."
"She was eager to get to the finish line."
Baseball, car racing, boxing, horse racing--these are metaphors that are constantly employed (and ones I have frequently heard) to describe tennis players. It annoys me to no end when commentators use one sport as a metaphor for another sport (that is such dead-lazy metaphor creation), but there is a bigger issue at hand than the very weak literacy skills of tennis commentators: Tennis will never gain the respect that these same commentators say they want it to have if they keep using other sports as reference points.
Can you imagine a football commentator saying "He's over the hundred yard line with an ace." Or a baseball commentator saying "It was a smash to right field." Or a boxing commentator announcing "It was an effective kick serve to the left jaw." Or how about a NASCAR announcer saying "Here she comes...she's at 40-love on the clock."
Of course you can't. Because football, baseball, boxing, racing, and soccer commentators and fans do not generally think of their sports as needing a reference point in another sport. And neither should tennis commentators. If you want to say that Sam Stosur's second serves kick like a kangaroo (I stole that line from a poem I once wrote), or that Amalie Mauresmo's backhand flows out of her (a wonderful metaphor I once heard about Mauresmo's entire game, not just her backhand)--not only is that effective use of metaphor, it is metaphor that does not insult tennis by presuming tennis needs a reference point in a "real" sport.