As the noise drew nearer, Dempsey readied himself for a collision. But his eyes remained fixed on left-hander Scott Bailes, who fielded a weak chopper near the mound and cocked his arm to sling the ball toward the plate.
Bailes' throw sailed a bit high, and it forced Dempsey to reach farther across the baseline than he probably preferred. As a result, his left side opened up toward Jackson, a man built like a Brinks truck. Dempsey left himself in no position to brace for the impact.
"Bo, being the football player at the same time, got down very low," says Dempsey, now a coach with the Orioles. "As he came in and hit me, he took my legs out from underneath me."
Dempsey then got caught in Jackson's redwood-like neck after he tried to transfer the ball from his glove to his right hand. But he was already too late making the exchange, and the attempted switch only made things worse.
"When his shoulder came by," Dempsey says, "somehow it just came so quick and bent my thumb back, snapped my thumb in the joint and put it back by my wrist."
His thumb dangled like a fish on a lure, and the impact with Jackson flung Dempsey backward about 10 feet toward the other end of the batter's circle. Amazingly, Dempsey broke only that thumb, but he spent six weeks on the disabled list.
As that play in 1987 shows, collisions at home plate stand as the most brutal and, often, most memorable plays in the game. Careers have been derailed and lives altered with just one forceful impact, which can easily dislocate a shoulder, shred knee ligaments or break bones.
Yet the consequences notwithstanding, a full-impact collision belongs in the same league as the brushback pitch. It's part of the game, and it's a play that's as exhilarating as a steal of home or a triple play -- even for the catcher.
Bring it on
Cubs catcher Michael Barrett has been involved in his fair share of collisions. Barrett has escaped full-force crashes without a scratch, and he's sustained bumps and bruises in others.
He's won some, he's lost some. But there's no better feeling, Barrett says, than maintaining control of the ball while withstanding the blow from a 200-plus-pound player.
"It's the best you can have," he says, "especially if it saves your team a run and it ends up helping your team win the game. It helps the pitcher give him a shutout, or it gives him that save."
On the other hand, losing a handle on the ball during a collision can be the low point for catchers. After a couple of accurate relay tosses or a cannon throw from an outfielder, the last thing they want to do is botch a well-orchestrated defensive play.
As graceful as those relay throws may be, time often ticks away on catchers, because they're trying to keep both eyes on the incoming ball while maintaining a feel for the baserunner.
"The hardest part is, you really have to not pay attention to the runner," Barrett says. "It's like that wide receiver going across the middle. If you hear footsteps as a receiver four or five times, you can't get scared to catch the ball."
Then, there's the matter of setting up at the plate. Each situation is different, Barrett says, depending on where the throw is coming from. Throws from right field tend to cause catchers the most trouble.
Just ask former Giants catcher Bob Brenly. His most severe knockdown came on a throw from that part of the field.
"I was catching a ball from right and [Braves second baseman] Glenn Hubbard was out of my line of sight," says Brenly, now a Cubs broadcaster. "So I just kind of sat down on home plate and cradled the ball against my chest just as he hit me in the left rib cage."
Ouch. Brenly broke a couple of ribs and missed some game action.
Sometimes, injuries like Brenly's are simply unavoidable, especially when a player of Jackson's size and muscle is chugging toward the plate. To minimize the extent of injuries, catchers are taught specifically how to position themselves at the plate.
"I was always told to plant the left foot straight up the foul line," Brenly says, "and as the ball starts getting closer to you, start shifting your body to the left to take away the chance of him getting the plate."
Problems arise when catchers don't point that toe toward third. If it's angled elsewhere, Brenly says, the outer part of the knee is exposed, and that's when catchers sustain the worst injuries.
Braves catcher Brian McCann nearly found that out the hard way earlier this season. In a game against the Diamondbacks, he fielded a throw from right as Eric Byrnes hustled in from third and began to slide.
The two collided and Byrnes thrust his shoulder into McCann, who lost the ball. Even worse, McCann heard a "pop" and figured he was done for the season. Fortunately, he wasn't.
"I got lucky because my knee was not square," he says. "I could have torn my ACL."
A lesson well learned. McCann still suffered a sprained left ankle and was placed on the 15-day disabled list as a result of the play. He says his cleats got stuck in the dirt and that his ankle -- not the knee -- took the brunt of the impact.
Turning the tables
Usually, catchers like McCann are the ones hobbling off the field after a home plate collision, but baserunners have sustained some significant injuries as well.
Sure, runners have speed and momentum on their side while catchers have none. How good are those factors, though, when runners are seemingly racing into brick walls?
Former Dodgers catcher Mike Scioscia, a 220-pounder, might have been the best at becoming that brick wall. Scioscia stood his ground well and knocked a few baserunners silly during his 13-year career.
"Scioscia was the best ever at blocking home plate," Brenly says. "He had it down to an art form, and he was a big enough guy that he could hang in there and take a hit. Usually, he would end up giving a lot more than he got."
In 1985, Scioscia was knocked unconscious yet hung onto the ball in a head-on collision with Cardinals first baseman Jack Clark, whose knees buckled as he headed toward the dugout. Clark had to be helped off the field.
Somehow, that collision wasn't Scioscia's worst, and it wasn't the worst for a baserunner against him. His best licking was saved a season later for Chili Davis, who charged Scioscia and came away with a separated shoulder.
"That was the hardest I've been hit, including my years of playing football," Scioscia says. "It was a heck of a collision. He was out that time. We were both out."
Reds catcher David Ross has been bowled over a few times, too, but his most severe injuries in a collision came in a Minor League game while he ran over another catcher, Corky Miller.
Ross, who played for Double-A Jacksonville at the time, rounded third in the 11th inning of a championship game against Chattanooga. His legs felt like rubber, so his upper body began to fall forward and into Miller.
"I went to run over him and I got a cut all the way up my arm," says Ross, pulling up his right sleeve to prove his story. "I had a big scar from hitting him."
Yes, indeed. At least he scored the game-winning run on that play, so that scar is more like a memento than a bad memory.
Still, if Ross keeps running like that, he'll surely get a couple more.
"I'll get more scratched up or dinged up trying to run over the catcher than sliding, because you get your whole body weight into it," he says. "Your body weight falls on him or his gear. You get scratched-up elbows and some of the equipment will catch you and cut you."
Practice makes perfect?
Well, the end result of home plate collisions is clear. But how do catchers even begin to prepare for a play that develops with such uncertainty?
Brenly says that a catcher really can't plan it out. There's no blueprint, no step-by-step guide for reeling in the throw, sustaining the blow and hanging onto the ball because each play unfolds differently.
Even then, it's a play that often means the difference between a win and a loss, so clubs have construed ways to simulate a home plate collision.
"You can have a pitching machine shoot the ball to you as you throw a tackling dummy against him," Brenly says. "That doesn't really simulate a 200-pound guy running at top speed and you're stationary."
No, it doesn't. The only way to truly prepare for a collision is to simulate the actual play with a baserunner approaching the plate. But who wants to do that?
Barrett does. He actually practices the play before the start of each season.
"Personally, I have a guy in the offseason who runs me over as I'm coming in," Barrett says. "One of things we'll work on is plays at the plate. We'll work on techniques."
If he gets anything out of that drill besides bumps and bruises, it's discipline. He learns to overcome that get-out-of-the-way instinct and stand his ground -- no matter who's coming at him.
A standout slam
Ray Fosse, a former Indians catcher, stood his ground at the 1970 All-Star Game at Riverfront Stadium, where his legacy became a collision with Pete Rose.
The game had ventured into the 12th inning, when Cubs outfielder Jim Hickman lined a single to center field. Royals outfielder Amos Otis tracked the ball down and launched a throw toward the plate, as Rose rounded third and hurled himself into Fosse.
Rose scored the game-winning run, and he permanently damaged Fosse's left shoulder. He also left Fosse with a legacy that he probably doesn't prefer.
"What bothers me a little is that the play kind of fed into the whole 'Charlie Hustle' thing, and it could have been pretty easily avoided," Fosse said in an interview a short time ago. He no longer wishes to discuss the incident. "I've heard Pete say he had no choice to do what he did, but I completely disagree."
As the seventh overall selection in the 1965 First-Year Player Draft, Fosse began his big-league career with much promise. He set career highs during that '70 season in batting average (.307), runs scored (62) and home runs (18), and that All-Star Game in Cincinnati was his first at age 23.
Unfortunately, Fosse completed his career as just a two-time All-Star, and he retired at age 32 because of that lingering injury. Thirty-six years later, the shoulder still gives Fosse trouble.
"I do think it had an impact on my career; just look at the numbers before and after," Fosse said. "But what's done is done. I wish it would just go away, to tell you the truth."
It probably never will, though. The crash is still flashed on highlight reels and considered the worst of all-time.
Dempsey's collision with Jackson ranks high on that list, too. Luckily for Dempsey, the pain in that thumb no longer lingers.
"I started to think how lucky I was that I only broke my thumb," Dempsey says. "Had I gotten the ball in time and done what I normally do -- get down on both knees and block the plate from the runner -- as fast as [Jackson] was running and as big as he was, he probably would've either separated or broke my shoulder, or even possibly broke my neck."
Kevin Yanik is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.