In the table below is a breakdown of how Pirates hitters and pitchers have performed in high leverage situations, divided by months. (WPA is Win Probability Added; it is expressed in terms of wins. It tells us how many games above or below average the Pirates gained/lost due to their production in high leverage - i.e. high pressure - situations. Explanation of WPA here.)

First, Pirates hitters:

In June and July, Pirates hitters did particularly well in high leverage situations, gaining the team 3.9 wins. Conversely, in August and September there has been a significant lack of clutch hitting, costing the team 2.2 wins.

Pirates Pitchers:

In April and May, Pirates pitchers were very effective in high leverage situations. Clutch pitching gained the team 4.8 wins. In August and September, Pirates pitchers have performed poorly in high stress situations and it has cost the team 1.8 wins.

Taken together, the drop-off in performance by both the pitchers and hitters in high leverage situations in August and September has cost the team four wins. In April and May, when the offense was in the tank, Pirates pitchers limited the damage and the team ended up gaining 3.3 wins from high leverage situations.

High Leverage Situations During High and Low Points Of Season

The Pirates season can easily divided into three distinct high and low points. On May 24 the team reached an early season low water mark of four games under .500. Starting on May 25 the Pirates turned their season around by posting a 43-23 record over the next 66 games. At the beginning of play on August 9, the Pirates were 63-47, 16 games over .500. On August 9, the Pirates began their "collapse." Since that date the Pirates record is 11-27.

In the table below I've calculated the Pirates WPA statistic for both hitters and pitchers in high leverage situations for each stretch of the season:

During the May to August hot streak, the Pirates gained 6.3 wins from their performance in high leverage situations. Since August 9, a lack of "clutchiness" has cost the team 4.3 wins.

Individual Player Performance In High Leverage Situations During The Collapse

So what players have performed most poorly in high leverage situations during the recent free fall? In the tables below I've calculated each players WPA in high leverage situations since August 9. I've included plate appearances so that we can see how many stressful situations each player has faced.

Hitters: (I've removed the pitchers except AJ Burnett who has had five plate appearances.)

During the slide, Garrett Jones as contributed almost a full win share, while Jose Tabata has subtracted .83 win share. Much used pitch hitters Travis Snider, Gaby Sanchez, Josh Harrison, and Jeff Clement have combined for -1.63 win shares.

Pitchers by Plate Appearances Against:

For those of us who follow this team every day it's not a surprise to see AJ Burnett, Jason Grilli and Jared Hughes combine for a -3.74 win share. Wandy Rodriquez has been a bright spot, posting almost a full win during the slide.

Conclusion

Based on the results of this analysis a great deal of the Pirates dramatic shift from winning to losing can be explained by their performance in high leverage situations. Of course this shift in fortune dovetails with a regression in pitching and hitting, generally (I looked at aggregate pitching and hitting statistics in this post). While a regression was predictable, but not inevitable, it is the extent of the drop-off that is truly stunning.

Consider following me on Twitter @DavidManel and Bucsdugout @Bucsdugout