This is exactly the point. (& the proper thing to do)
I saw a Landsdorp tennis channel tip where he was hitting "moon balls" or lobs or whatever to some kid who was learning to take balls on the rise....to not back up. What a great way to improve taking the ball on the rise & eventually marginalize a moonballer. So...I took my kid out & I hit several buckets a day for a couple of weeks until he was comfortable taking ALL (every damn one) lob/moonball (whatever) on the rise & thru the strike zone.
My kid doesn't hit it hard enough to "hit winners" off these shots, but he normally takes enough time away that he's able to win the point on the next shot or two. A kid who takes it on the rise, will yawn when they see a moonballer & will take delight in watching them run all over the court because of the time he's taken away from them.
Bottom line....thank the moon baller. Use it as a training tool. But.....if you're worried about a 9 or 10 y/o winning every match, then this of course won't work. But if you have them NOT back up (ever) against the moonballer and take EVERY moonball on the rise then after a month or two (took my kid maybe two tournaments) they begin win more moonball points then they lose. But more importantly, they are MUCH better at taking balls on the rise.
How many hundreds of dollars for lessons or how many hours of training would one blow for a 9-10 y/o to learn (to ALWAYS) hit these kind of balls on the rise?
Heck...instead watch 10 minutes of Landsdorp, hit a couple of buckets of lobs a day for two weeks to your 9 y/o kid & have them play a couple of 10s or low level 12s tournaments & your kid will be hitting it on the rise like Davydenko. & to those who say it's "not easy" to learn how to handle moonballers....so what?
Added benefit.....recreational adults like to hit with 10 & 11 y/o kids who take it on the rise properly....they keep the damn point going instead of (so many 9 & 10 y/o kids who are) always backing up to the fence & then blasting wild (but technically correct) forehands all over the place.
So seek out the moonballers & pushers....don't run away....don't whine....they are your friend. (But if one is a moonball whiner then the kid will be a moonball whiner & the adult is probably more concerned about the 9 y/o winning....or "beating" the moonballer than on his kid actually improving.)
Just my ignorant opinion.