The play at the plate is one of the most exciting and dangerous plays in baseball. When the base runner, ball and catcher all meet at the same place at the same time, just about anything can happen.
Unstoppable force, meet immovable object.
It's a play that has always been a part of the sport, yet occasionally rises up to spark controversy.
In one famous incident, Pete Rose ran over catcher Ray Fosse for the game-winning run in the 1970 All-Star game. Fosse suffered a separated shoulder on the play, and Rose was criticized for taking such a take-no-prisoners approach in an exhibition game.
More recently, a couple of high-profile incidents have brought controversy to the play, with calls from some corners to either outlaw catchers from blocking the plate, outlaw runners from attempting to flatten said catchers, or both.
In August of 2010, the Cleveland Indians lost rising star Carlos Santana for the remainder of the season to an injured knee when Boston's Ryan Kalish slid hard into his planted left leg.
And last May, San Francisco Giants star Buster Posey was lost for the season when Florida's Scott Cousins launched into him with enough force to break his leg and tear ligaments in his ankle.
Interestingly, despite such high-profile incidents, you'll be hard-pressed to find many catchers supportive of the idea of outlawing the play.
"Some guys choose to give up the plate, and then take it away," says Indians catcher Lou Marson. "I like to take it away from the get-go, because I believe that if I'm over the plate, you're gonna slow down a bit if you see me standing there. . I know a lot of teams are telling their guys to not block the plate, but I kinda like contact to be honest with you."
Los Angeles Angels manager Mike Scioscia, who caught for the Dodgers for 13 years, more or less agrees.
"Unfortunately you can't pick and choose the parts of catching that you like," Scioscia says. "If you're going to be a catcher you have to find a way - maybe not to put your body in the line for a collision - but find a way to make tags at the plate. Some guys are more aggressive, some are less aggressive on that play, and at times guys get banged up on it."
"That's what happened to Carlos," Marson says. "He went to get the ball like this (leans to his right) and his (left) leg straightened, and you're in a weak position."
If the throw is coming from right field, Marson says, the catcher should position himself three steps behind the plate - maintaining better peripheral vision of the runner coming in from third base - and walk into the play. (The Santana play came from right field, and the Posey play from shallow right-center. Neither catcher started the play from behind the plate.)
Posey, 25, an elite hitter and smart player adept at calling a game and working with pitchers, is nonetheless inexperienced as a catcher, switching from the shortstop position as a sophomore at Florida State. That inexperience may be one reason the Giants asked him not to block the plate - a full 10 months before the Cousins play. It may also be a reason Posey appeared awkward on the play.
With everything a catcher is responsible for on the baseball field, it is a huge loss to a team when a good one goes down with an injury. So short of outlawing the collision at home plate, what can be done to keep catchers safe?
Rob Leary, the minor league field and catching coordinator for the Cleveland Indians, stresses fundamentals as a way of reducing, if not eliminating, injuries.
"Obviously you want to get outs, you want to prevent runs," he says. "That's what defense is all about. But you want to be smart about it. We want these guys to get into a good athletic position where they can react to the ball and make the tag in a good athletic position of strength, so the fundamental side is taken care of, but also from a health perspective."
And sometimes, depending on the situation of the game, the catcher just has to concede the run, to live to play another day.
"You cannot try to be the hero," says Seattle Mariners catcher Miguel Olivo. "When somebody is coming to home plate, you need to know how to block home plate, or how to take the punch when somebody comes. . But if you don't pay attention, you're going to get hurt."