As a kid, like most American boys of my generation, I spent a lot of time with bat and ball. We played most of the playground games. Over-the-line. Work-up. Pickle. But also just throwing and catching.

And I always knew what sort of ball we were using.

We preferred a hard rubber ball that was the standard nine inches around, but it was significantly lighter than the leather ball with hard center that big-leaguers used. The one that weighs about 5.5 ounces.

The lighter ball probably was introduced to us by our parents, because it was less likely to travel long distances or break things when it struck them. Windows. Bones.

Eventually, at the age of 9, 10, 11, I conceived a fear of what we called the “hardball.” I remember being constantly amazed at how hard the hardball was. “This thing could hurt people.” I thought that.

And though I never got around to playing organized baseball before high school, had I done so it would have been for the local Elks League — which used the lighter ball — as opposed to Little League, which used the hardball. I was not eager to get in a batter’s box when a pitcher was throwing a hardball towards me.

The hardball was dangerous. Was then. Is now.

This all came back to me when Brandon McCarthy of the Oakland Athletics suffered a fractured skull when a line drive struck him in the head.

What surprises me about this?

That so much baseball has been played with relatively few incidents of this magnitude.

In the long history of Major League Baseball, only one player has died as a direct result of being struck by a baseball — Ray Chapman of the Cleveland Indians, hit in the head by a pitch by Carl Mays in 1920.

Mike Coolbaugh, a coach for a Triple-A minor-league team, was killed by a hard-hit foul ball in 2007.

But that is about it, when it comes to on-field fatalities cause by the hardball.

Still, doesn’t it feel as if we are on the verge of something dire?

Players are bigger and stronger than ever. Pitchers throw harder, and nearly every batter now swings as hard as he can on every pitch. Balls come rocketing off bats, and pitchers begin their delivery 60 feet and 6 inches from home plate — and end it significantly closer.

A third baseman can be closer than 90 feet to home, and the base coaches are significantly closer. Perhaps 70-75 feet, in some cases.

A hard-hit ball can get to them very quickly. Talking fractions of seconds here.

A scary part of McCarthy’s injury — and here is video of it, if you want to see it — is how the ball ricocheted off the man’s head over to third base, where it was picked up and thrown to first for an out.

(What Ray Chapman was hit by a pitched ball, it bounced off his head so violently that it was fielded by infielders, though it was never actually in play.)

One of the reasons big-leaguers don’t use metal bats (and never will) is that metal increases the speed of a batted ball even more. I’ve done a story or two on this, and I distinctly remember MLB players saying “someone would get killed” if metal bats were used at the highest level.

I worry about pitchers, in particular, and McCarthy’s injury seems to have prompted at least some discussion of protective headgear for pitchers.

It seems as if McCarthy is recovering, but during the process an official with the Athletics described his injuries as “life-threatening.”

It’s that hardball.

If you don’t think it’s dangerous, go pick one up.