Seth Maness and Double Plays

The 2013 Cardinals’ season featured many compelling storylines, but perhaps none so remarkable as the team’s incredible success with rookie pitchers. While Shelby Miller and Michael Wacha each had excellent seasons as starters, the rookies’ emergence was especially important in the bullpen, where they accounted for a full 55.9% of total innings pitched. The rookies helped the Cardinal bullpen improve its collective FIP from 3.92 in 2012 (ranking 11th in the National League) to 3.26 in 2013 (ranking 2nd behind only the Braves). The performance of the Cardinal rookie relievers was a popular talking point during the playoffs, as flamethrowers Trevor Rosenthal, Kevin Siegrist and Carlos Martinez combined to form a formidable late inning trio. With all of these impressive young arms, Cardinal fans might be surprised to find which non-closing young reliever found his way into the most crucial game situations throughout the course of the season. Behind closer Rosenthal and one-time closer Edward Mujica, the highest average leverage index for a Cardinal pitcher with at least 15 IP came from none other than ground ball specialist Seth Maness.

Maness was selected in the 11th round of the 2011 draft out of East Carolina University, where in 2010 he had been named the pitcher of the year in Conference USA. He moved quickly through the minors, playing at three levels after the draft in 2011 to finish at high A Palm Beach. He finished 2012 at AA Springfield and took home the Cardinals’ minor league pitcher of the year honors. At this point the Cardinal prospect community started to take notice of him. In October, 2012 VEB’s own jeff_underscore wrote a piece for Future Redbirds calling Maness the minor league breakout pitcher of the year. Maness had upper 80’s velocity and a troublingly low strikeout percentage but incredible command low in the zone and a nifty changeup that allowed him to consistently generate ground balls and never walk anyone. In 2012 he pitched 169.2 innings and allowed a total of 10 walks. In the words of John Sickels’ The Baseball Prospect Book 2013, Maness was truly a "dilemma for prospect evaluators".

In 2013 Maness had just 4 starts at AAA Memphis before getting the call to help an ailing St. Louis bullpen. He made his debut on May 3 in a game against the Brewers, facing 3 batters and recording 3 groundouts. Nearly 2 weeks later, after the game on May 14, Maness had faced a total of 11 batters in his brief career and not one PA had ended with anything other than a ground ball. He had also picked up his first 3 double plays as a major league pitcher. It may have been around this date that the wheels began to spin in Mike Matheny’s head. At any rate, within a few weeks it had become clear: Seth Maness was the Cardinals’ double play specialist.

In researching this piece I googled the phrase "double play specialist" to try to see if this role had ever been employed in the past. The first four results were all articles about Seth Maness. After that were Call of Duty Youtube videos, instrument vendors and football articles. If there were ever a double play specialist in the past, I wasn’t able to find him with this (admittedly limited) approach.

By the end of the regular season, 38.8% of the time Seth Maness had come into a game there had been a man standing on first base. This percentage was of course tops on the team. Maness, despite the lowest strikeout percentage of all Cardinal relievers, had continually found himself brought into the game during crucial, high-leverage moments with men on base. Matheny’s reasoning was almost certainly that Maness offered the best chance at ending the threat with a ground ball double play. However, as Maness’s strategy centers around pitching to contact, and any ball put in play has a chance to turn into a hit, it seems logical to question whether going to Maness in a high leverage situation is the correct decision.

Before we look into what the Cardinals’ strategy should be moving forward, let us take a moment to look at what already happened in 2013, and acknowledge that, for the most part, bringing Maness in for double play situations worked out tremendously for Mike Matheny. Maness was on the mound for a total of 52 PAs featuring less than two outs and a man on first base. In these double play situations, Maness recorded the double play 16 times, 30.8% of opportunities. The league average percentage of converting on a double play opportunity (GDP%) was just 11% in 2013. Maness‘s mark was tops in all of baseball. Maness was especially incredible with the bases loaded. In 8 PAs with the bases loaded and less than two outs, Maness converted a double play 6 times! Incidentally, all of those occurred with one out in the inning. Seven times Maness faced a batter with the bases loaded and one out. Six times he ended the inning on a double play. That is just amazing and -- no matter how you slice it -- very lucky. In fact, when looking at his overall rate of generating double plays, it is hard to say that Maness wasn’t very lucky all season.

Maness finished the year with the second highest ground ball percentage (GB%) in baseball, at 68.4%. This fact accounts for part of his high GDP% but, as we’ll see, not all of it. I was unable to find the overall rate at which ground balls are converted into double plays, so I had to make a crucial assumption in this next section. Specifically: I assume that PA outcome statistics (i.e batted ball, K%, etc) are the same in double play situations as they are on average. As previously stated, the average GDP% in 2013 was 11%. The average K%, BB% and HBP% were 19.9%, 7.9% and 0.8%, respectively. That leaves 71.4% of PAs ending with a batted ball. Of this fraction, 44.5% were ground balls, giving us a total of 31.8% of PAs ending in a ground ball. If this number remains the same in double play situations, then 34.6% of ground balls with a man on first and less than two outs resulted in a double play.

Maness had a K%, BB% and HBP% of 14.1%, 5.2% and 0.4%, respectively, meaning 80.3% of his PAs ended with a batted ball. Multiplying by his ground ball rate, we find that 54.9% of his PAs ended in a grounder. If his rate of converting grounders into double plays equaled the average, we should only have expected him to have a GDP% of 19.0%! That’s nearly 12 points lower than the number that he actually posted. Unless there is a good reason why the Cardinals’ defense was especially good at turning ground balls into double plays (doubtful, as our infield defense was average at best), this result certainly seems to indicate that, even with his high GB%, we should not expect Maness to continue getting double plays at the rate he had in 2013. That’s bad news for Maness and the Cardinals, because we also should expect his GB% to fall, perhaps significantly.

I mentioned before that one of Maness’s signature attributes in the minor leagues was his excellent command which consistently limited walks and generated ground balls. However, his overall minor league GB% was only 52.5%, 16.9 points lower than his 2013 mark in the majors. It is possible that the coaching staff asked him to emphasize his sinker more in the majors, or that being in relief allows him to get more action on his pitches, leading to more grounders. However, we should hesitate before assuming that Maness will continue to see as many grounders as he did this past season. Over the past three seasons combined, only seven relievers have averaged a GB% above 60%. It is possible that Maness will remain among the league leaders in this statistic during his career, but after just one season we should hesitate before placing him among the elite ground ball relievers.

I will keep the summary brief because this post has ended up longer than I had expected. Seth Maness had a truly remarkable season in 2013. He had the second highest rate of ground balls in the majors and, thanks to some combination defense and good luck, the highest rate of double plays. However, his success with the double play may have caused Mike Matheny to place too much trust in him, causing Mike to call on Maness in some very high leverage situations. With Maness set to play a potentially large role in the bullpen in 2014 and beyond, Matheny should acknowledge the good fortune that the club experienced with Maness last season and adjust his expectations accordingly.

All of Maness's minor league batted ball statistics were taken from Minor League Central. The game log statistics were taken from Baseball Reference. The league average GDP% was taken from this article on CBS Sports. All other statistics were taken from Fangraphs.

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