There are many ways the defensive team can execute a triple play, most occurring with runners on first and second base. Typically, a ball hit to the shortstop or third baseman is fielded, the runner heading to third is forced out or tagged out, the ball is thrown to second base for a force play, and then finally to first to throw out the batter. Another likely sequence is a line drive to the shortstop or second baseman that is caught without the runners noticing or after they have taken large leads (as in the case of a hit and run), the runners then being forced or tagged out when they fail to tag up.
Triple plays are relatively rare, since a triple play requires at least two baserunners, no outs, a batted ball hit in a way that allows it to be fielded cleanly so that three baserunners can be put out or unusual incompetence in baserunning, and quick action from the fielders to perform. The unassisted triple play, a triple play in which only one fielder handles the ball, is the least common type of triple play, and is arguably the rarest occurrence in baseball: it has happened only 15 times since 1900 at the major league level. Triple plays, even of the unassisted variety, are not extraordinarily difficult for major league fielders to achieve; their rarity is due to their dependence on specific circumstances arising in a game.
According to the Society for American Baseball Research, there have been 701 triple plays in Major League Baseball since 1876. The most recent triple play was recorded on September 1, 2015 by the Colorado Rockies against the Arizona Diamondbacks at Coors Field.
In 1973, Baltimore Orioles third baseman Brooks Robinson started two 5-4-3 triple plays: one on July 7 against the Oakland Athletics' Gene Tenace, and one on September 20 against the Tigers' Frank Howard. In both cases, Bobby Grich was the second baseman.
Playing against the Boston Red Sox on July 17, 1990, the Minnesota Twins became the first (and to date the only) team in baseball history to turn two triple plays in the same game. Both triple plays were 5-4-3 plays (Gary Gaetti - Al Newman - Kent Hrbek). Jody Reed was the first out in the fourth inning play and the final out (batting) in the eighth inning play. Despite their defensive heroics, the Twins lost the game 1–0.
While playing with the New York Yankees in 1982, Bobby Murcer, Graig Nettles, and Roy Smalley got caught in a bizarre 2-5-3-1 triple play while facing the Minnesota Twins. Smalley had struck out (Out #1), and meanwhile the runners from 1st and 2nd had taken off in an attempt to steal second and third. The ball was thrown to 3rd (played by Gary Gaetti). Gaetti chased Murcer back to 2nd base and tagged him but he was called safe. Gaetti then threw the ball to 1st baseman Kent Hrbek to tag Nettles who was caught between 1st and 2nd (Out #2). During this, Murcer had attempted to take off from 2nd again. The ball was thrown from Hrbek to 3rd base to pitcher Terry Felton, who was now covering 3rd base and tagged Murcer (Out #3).
The Yankees also turned one of the more bizarre triple plays in history. On April 12, 2013, with runners on first and second, Baltimore third baseman Manny Machado hit a sharp one-hopper to Yankees second baseman Robinson Cano. Cano fielded the ball and flipped to shortstop Jayson Nix, retiring Nick Markakis. Instead of going to first for a routine double play, Nix opted to fire to third baseman Kevin Youkilis. Baltimore's Alexi Casilla was caught between second and third. Youkilis chased Casilla back towards second, beginning a rundown. Youkilis tossed back to Nix, who returned the throw to Youkilis, who tagged Casilla for the second out. While this going on, Machado had rounded first and was attempting to advance to second. After tagging Casilla, Youkilis fired to first. Yankees' first baseman Lyle Overbay, now catching Machado in a rundown, pivoted and threw back to Cano, who tagged Machado sliding into second base for the third out. The play was scored 4-6-5-6-5-3-4, the first of its kind in Major League history. 
On May 9, 2015, with runners on second and third, St. Louis Cardinals catcher Yadier Molina hit a line drive that was snagged by Pittsburgh Pirates second baseman Neil Walker. Walker then fired the ball to third baseman Jung Ho Kang to double off the Cardinals' Jhonny Peralta for the second out. Kang, after a moment's hesitation, then threw back to Walker to retire Jason Heyward for the third out. It was the first 4-5-4 triple play in Major League history, and the second triple play turned by the Pirates in as many seasons.
Unassisted triple plays
The rarest type of triple play, and one of the rarest events of any kind in baseball, is for a single player to complete all three outs. Typically, this is achieved when an infielder catches a line drive near second base (one out), tags the base to double up the runner who started play there (two out) and tags an advancing runner before he can return to his original base (three out).
The most recent unassisted triple play in Major League Baseball occurred on August 23, 2009 when Eric Bruntlett of the Philadelphia Phillies turned the first ever game-ending unassisted triple play in the National League, in a game against the New York Mets. In the bottom of the ninth inning with men on first and second, Jeff Francoeur hit a line drive up the middle, where Bruntlett (substituting for Chase Utley) was covering with both men moving. Bruntlett caught the ball, tagged second to double up Luis Castillo and then tagged Daniel Murphy from first, thereby completing the triple play. This was only the second game-ending unassisted triple play in MLB history and the first since 1927.
Unfielded triple play
Political columnist and baseball enthusiast George Will, in a baseball quiz in Newsweek for April 6, 2009, p. 60, posed one hypothetical way that a triple play could occur with no fielder touching the ball. With runners on first and second and no outs, the batter hits an infield fly, and is automatically out: One out. The runner from first passes the runner from second and is called out for that rule's infraction. Two outs. Just after that, the falling ball hits the runner from second, who is called out for interference: Three outs.
Whenever a batter or runner is out without a fielder touching the ball, rules book section 10.09 provides for automatic putouts to be assigned by the official scorer. In this case, the first out would be credited to whoever the official scorer believes would have had the best chance of catching the infield fly. The second and third outs would be credited to the fielder(s) closest to the points the runners were, when their respective outs occurred. Under the scenario described above, the same fielder (the shortstop, for example) could be credited with all three putouts, thus attaining an unassisted triple play without having touched the ball.
- TRIPLE PLAY DESCRIPTIONS By Many SABR Members and Coordinated By Chuck Rosciam and Frank Hamilton (1970-2008)
- "Baseball's Triple Plays – Trivia & Miscellanea". August 28, 2007. Retrieved April 7, 2008.
Minnesota Twins turned TWO triple plays in the same game against the Boston Red Sox on 7/17/1990, 4th & 8th innings. Only time that two TP's occurred in a game.
- Boston Red Sox 1, Minnesota Twins 0
- Nash, Bruce; Zullo, Allan. The Baseball Hall of Shame 4. Pocket Books. pp. s 35–36. ISBN 0-671-74609-X.
- Brooks Robinson Quotes
-  Bruntlett joins rare company | MLB.com