Few things in baseball are as emotionally crushing as a crucial error from your team in a tense late-and-close situation. A booted grounder in the ninth inning, a dropped lazy fly ball with the bases loaded and two outs—these are the events that can make fans absolutely sick to their stomach. All at once, a promising multiple-run lead can evaporate in an instant, and not by virtue of the merits of the opposition, but solely because of the bumbling, bone-headed clumsiness of your own beloved shortstop or left fielder.

The 2013 season had no shortage of these heart breaking plays, and I’d like to identify the worst of the worst.

To define “most costly” I’ll use two measurements of the in-game situation: Leverage Index and Win Probability Added. For those not familiar with these metrics, our Hardball Times glossary defines Win Probability Added (or WPA) as “the impact each specific play has on the team’s probability of winning” and Leverage Index (LI) as “a measure of how critical a specific batting situation is.”

First let’s look at the errors that occurred in the most crucial game situations, or, in other words, situations with the highest Leverage Index:

Most costly errors by LI 2013

White Sox fans will probably remember this most crucial error of the season, as it’s likely they hadn’t lost all hope of something better than a 99-loss season at this point.

Reliever Jesse Crain had loaded the bases in the eighth inning of a game that the southsiders were actually winning 5-4. For a moment it seemed as though Crain and the Pale Hose would escape the outing unscathed, as the right-hander managed to strike out George Kottaras and Jarrod Dyson consecutively before the Royals’ shortstop Alcides Escobar stepped to the plate.

I’m not entirely sure what happened on this play, but it appears as if the ball takes unexpectedly leaps past Alexei Ramirez, perhaps off his wrist or knee ( or even through his legs). The ball then trickles into left, allowing both David Lough and Elliot Johnson to score the tying and go-ahead runs. The Royals would then retire the Sox 1-2-3 in the ninth for the victory. With a stratospheric LI of 7.9, no error from the 2013 season occurred at a more critical situation than did Alexei’s flub on June 23 in Kansas City.

That play also cost the White Sox more than 50 percent of their Win Probability. As staggering as that figure might seem, it was not the worst drop in WPA caused by botched grounder this year.

Most costly errors by WPA 2013

# Fielder Team Date Inning Bases Outs Score LI WPA 1 Brandon Belt Giants Jul 26, 2013 9 1-3 2 1 5.8 -70.5 2 Alexei Ramirez White Sox Jun 23, 2013 8 123 2 1 7.9 -50.6 3 Andrelton Simmons Braves Sep 17, 2013 9 -23 1 1 6.0 -47.2 4 Logan Forsythe Padres Jun 26, 2013 13 12- 2 tie 4.3 -45.1 5 Brandon Snyder Red Sox Jul 6, 2013 9 1-3 2 1 7.1 -44.1 6 Tom Wilhelmsen Mariners May 20, 2013 9 1-3 2 1 7.2 -41.3 7 Jarrod Dyson Royals Sep 23, 2013 7 1– 1 1 2.6 -39 8 Elvis Andrus Rangers Jun 9, 2013 9 1– tie 2 7.4 -37.9 9 Jimmy Paredes Astros May 17, 2013 9 123 2 tie 6.4 -35.1 10 Brandon Crawford Giants Jul 8, 2013 16 1-3 2 tie 4.8 -35.0

Brandon Belt’s error on the evening of July 26 wasn’t technically as dire as Alexei’s a month earlier (at least, not according to Leverage Index). It was the ninth inning and his Giants were also up by just one run, but the bases only held two Chicago Cub base runners as closer Sergio Romo went to a full count on Anthony Rizzo.

On the eighth pitch of a very emotionally tense at-bat, Rizzo scorched a hard-hit grounder down the first base line. Belt, on his knees, could not prevent the ball from zipping past him into the right field corner. The Cubs had speed on the basepaths, with both Julio Borbon and Junior Lake scoring the tying and go-ahead runs to take a late lead over the Giants. It was a tough error, but with Belt directly in front of the ball’s path, it was clearly the only ruling the official scorer could make.

Cubs closer Kevin Gregg would then finish off the Giants in the bottom half of the inning and Belt’s mishap proved to be the difference in the outcome of the game. That singular play cost his team over 70 percent of win expectancy.

Historical perspective

Interestingly, this year’s standout errors from both Ramirez and Belt appear to be rather significant in history, or at least dating back to 1974. Alexei’s error occured in the sixth most critical situation by LI in that time frame, while Belt’s -70 WPA is an impressive third greatest in terms of loss of win expectancy:

Most costly errors all-time (sortable)

# Fielder Team Date Inning Bases Outs Score LI WPA 1 Bengie Molina Angels Sep 3, 2003 9 12- 2 1 6.8 -82.14 2 Luis Castillo Mets Jun 12, 2009 9 12- 2 1 6.8 -81.79 3 Brandon Belt Giants Jul 26, 2013 9 1-3 2 1 5.8 -70.54 4 Darren Holmes Brewers Sep 9, 1992 9 1-3 2 1 5.8 -70.36 5 Cristian Guzman Nationals Apr 21, 2005 9 123 2 1 9.7 -64.14 6 Brad Lidge Phillies Aug 15, 2009 9 1– 1 5.4 -61.72 7 Jim Thome Indians May 19, 2002 9 -23 2 1 6.8 -59.3 8 Donnie Smith Rangers Sep 17, 2000 8 1-3 3 10.2 -56.86 9 Roger Cedeno Tigers Aug 10, 2001 6 123 2 6.7 -53.18 10 Brandon Crawford Giants Apr 8, 2012 7 123 1 1 9.7 -50.85 11 Alexei Ramirez White Sox Jun 23, 2013 8 123 2 1 7.9 -50.64 12 Chris Valaika Pirates Jun 10, 1997 8 123 2 1 7.8 -50.59 13 Alex Gonzalez Marlins Jul 18, 2001 9 12- 1 1 7.1 -50.35 14 Jim Thome Indians Aug 29, 1997 8 1-3 2 3 7.1 -49.2 15 Carlos Guillen Tigers Jun 3, 2010 8 — 6 5.0 -47.56

The greatest loss of WPA on an error occured on Sept. 3, 2003, when Bengie Molina dropped a throw to the plate in the bottom of the ninth inning, allowing two runs to score resulting in a Minnesota walk-off win. There is no video of the play at mlb.com, unfortunately, but recaps from the game tell the story of Dustan Mohr lowering his shoulder before the play at the plate and breaking two of Molina’s wrist bones on contact. Molina would not play again in the 2003 season.

The second greatest loss of WPA on an error was a bit more recent, however, so there is video of the event available for those non-New Yorkers among us, who may not have the incident burned to memory:

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Certainly, dropping a routine infield fly ball with the bases loaded would seem to be a more deserved error than dropping a ball while experiencing a season-ending injury involving broken bones.

Of course, no discussion of the costliest error of all-time would be complete without mentioning baseball’s most recognizable error of all time—the one that famously rolled “behind the bag” on Saturday, Oct. 25, 1986. All of these tables above have been limited to regular season, but also have only considered the game at hand, rather than the impact on the team’s season.

Baseball-Reference scores the Buckner play as a loss of about 40 percent of win expectancy for that game. A huge loss on its own, but if we were to apply Dave Studeman’s method of combining in-game LI with Championship Index, would any other World Series error even come close to approaching the Buckner error’s criticality?