She is good in tennis, because while he is not vs She is good at tennis, because while he is not

Some examples from the web:

• I mean, no one actually thought he was saying goodbye to tennis for good, because that's a crazy thing to say when retiring.
• But in tennis, they're forced to interact.
• She is all that is good in the world.
• Lettered in tennis, squash, and served as editor of the school newspaper.
• Dude, you had to play me in tennis, now horse.
• In tennis, you attack at the point of weakness!
• Yesterday they didn't play tennis, because it rained.
• I mean, that's not old, but in tennis, that's old.
• So, in tennis, every point is either good for you and bad for the other person, or good for them, bad for you.
• In tennis, if a ball hits the line, it is just as much 'in' as if it had been in the centre of the court.
• I think ithelpedmy tennis, because l did work hard.
• Nevertheless, I am more worried about the media's ability as the watchdog of what is good in society, because the interests of both are more and more exclusively about profit.
• The report is good in many respects.
• Cooperation is good in all areas.
• After tennis, a dip in the pool, not in the sea, because it's dangerous.
• Well, the fun's about to end, Jean Claude, because while we've been standing around chatting, our other master spy has been effortlessly breaching your compound's security.
• You're doing this, because while we're trying not to die, we still need to live.
• No, but he was going somewhere, because while we were on the phone, I literally bumped into him leaving the building from the private entrance.
• But you took me back, because while I was gone, somehow you learned to accept the bad with the good.
• Now see, in Duolingo, because while you learn you're actually creating value, you're translating stuff - which for example, we could charge somebody for translations.

Some examples from the web:

• I mean, no one actually thought he was saying goodbye to tennis for good, because that's a crazy thing to say when retiring.
• They know about us: that you're good at tennis, that you...
• She is good at playing the guitar.
• She is good at speaking English.
• She's good at tennis too.
• She is so good at making people believe she is good with people.
• Mr. Smith, because my son is good at football... he has opportunities that otherwise would not be his.
• But she is good at her job?
• So she is good at keeping a straight face, and she vigorously crushed any attempt in the House of Lords for the British people to have a referendum.
• She is better at writing than our U.S. presently amateur number two is at tennis.
• Yesterday they didn't play tennis, because it rained.
• I wanted to become good at things, I wanted to become at tennis and school and grades.
• I not only play tennis, I'm good at horseback riding, golf, swimming, shooting, pretty much everything.
• I think ithelpedmy tennis, because l did work hard.
• Is she there because she is good at her job, or is she there because she is part of a quota?
• Cyril, miraculously, is good at something, and...
• The manager is good at dodging responsibility.
• Ayumu is good at cooking anyway.
• They say not everybody is good at it.
• I hear your friend is good at the phone.