It would be easier to return the tennis ball for the simple reason that you wouldn’t be scared of getting hit by it.
It takes a long time to not be scared of getting hit by a baseball, now imagine one coming at 100 mph. Your first thought would be on bailing, not swinging the bat.
Fear is certainly a factor, but it's not an overrulling one.
Here's how I see it -
The average person does not have the skill to do either, however, what is more likely for the average person to get lucky to where they can accomplish either action?
Hitting the baseball.
If only for the fact it requires fewer actions to do. Not to b*stardize the skill of actually hitting a 100MPH pitch, but you only have to swing in a stationary position to make contact with the ball. Now, like I said above, no average person has the skill to do that, but they could get lucky if they just happen to swing the bat at the precise moment the ball is the vicinity of that action. If only by luck and absolutely nothing else.
Now, actually
returning the same speed tennis serve is another thing, altogether.
It's not just a matter of standing in a stationary position and hoping to get lucky by hitting it, which again, would be entirely luck for the average person to do. The homie
@sportscribe just dropped a dope story about his pops-in-law (avid tennis player, himself) who played a former pro, and said he was hearing the serves, but didn't see the balls. Which goes to show, the same degree of fear might not be present, but what hope do you have of ever hitting it if you can't see it (and that's the perception of someone who plays tennis)?
To actually hit a tennis serve you have to move x-amount of feet across the baseline to anticipate where the ball is going to bounce up from within the service box. Meaning, not only do you have to anticipate the location at which the ball is going to bounce up from, but you've also got to move your feet in that direction - that requires another factor of luck that isn't present in hitting a baseball, where the ball merely has to travel within strike zone.
Now, the differentiator here is, hitting the tennis ball back over the net and landing it in-bounds. That is something which goes beyond luck and you'd need skill to pull off. You'd have to have the appropriate amount of touch to swing the raquet to get the ball over the net and in-bounds. It's not a matter of just swinging the raquet, hitting the ball and magic happens when the ball goes back over the net and lands within the singles lines. You actually have to have control over hitting it, which if you've ever hit a tennis ball, if you swing as hard as you can without control, the ball is going to end up in the bleachers.
The landing space is much smaller on a tennis court than it is on a baseball field.
The average person would find it hard to even make a tennis serve, hitting it over the net and landing it within the service box, merely because they don't know to control the ball. Now just imagine the average person trying to control a tennis ball that's travelling at 100MPH.
TRY AGAIN
.