Seth Maness has been an absolute workhorse for the St. Louis Cardinals' bullpen this year, often coming into games in the worst situation imaginable - men on base and less than two outs - largely because of his innate ability to produce grounders at a prodigious rate. In the regular season this year, Maness recorded 186 outs. If his percentages stay true, then his 68.4% GB rate would have produced 127 of those outs this year. However, Maness also produced 16 ground ball double plays this year, so it could have been over 140 of his 186 outs coming via the ground ball. Not only is that true, but Maness came into games on thirty separate occasions with at least one man already on base. In those 30 games, a total of 52 men were on base when he entered a ball game. Maness coaxed a ground ball double play in 11 of those 30 games after coming in with inherited runners, allowing just 7 of 52 inherited runners to score this season.
In the 8 post-season games in which Maness has pitched, he has come in 6 times with at least one man on base - for a total of 11 inherited men on base. Maness has gotten just 2 double plays and allowed 6 of the 11 men to score; he has allowed a run or more on 5 separate occasions out of 6. He has one blown save and allowed the winning runs to score last night on Jonny Gomes' 3-run blast.
Why is this happening?
Theory #1, Lack of Luck
In baseball, as in any sport, when you get into super small sample sizes like 4 2/3 innings, sometimes you just get a bit unlucky. If you only ever saw Adam Wainwright pitch in his two back-to-back starts against Cincinnati on August 28th and September 2nd, then you would have no way of knowing that he's a Cy Young Award candidate, by seeing 15 runs allowed on him in just 8 innings of ball. If you only watch the post-season, you would have no clue that Matt Carpenter led either league in hits this year with 199, as his hitting in the World Series (at a .278 average) is easily his best round of the post-season.
Theory #2, Lack of Skill
Some people believe that the things pitchers can control are strikeouts, walks, and home runs. While Seth Maness does a great job of keeping the ball on the ground, and allowing less home runs per nine innings than many relievers; when he does allow fly balls, he allows homers at a higher rate than most pitchers in the league - over 16%! Similarly, Maness usually has a very good K:BB ratio, but his K rate is well below average, leaving him more susceptible to balls in play. Maness struck out just 61% of the players a league average reliever does - just barely more than one every two innings.
That said, he was above a league average reliever this season, especially if you regress his home runs to the mean - or take out the "luck" involved there.
Theory #3, Just "Done"
You might hear that young pitchers often have a pitch count or innings count. This is in an effort to help young pitchers get accustomed to throwing more innings per season over time. As a freshman in college in 2008, Maness threw 98 1/3 innings. The next year he played both Cape Cod League Summer ball and baseball for his school, throwing a total of 141 innings. That is quite a large jump, but Maness seemed to handle it just fine, with no arm troubles. The following season, he did not play summer ball (or at least it wasn't listed anywhere I can find). He threw just 101 1/3 innings as a junior. With his previous high of 141 innings, it should be no problem that he threw a total of 158 innings as a senior in college and then in short-season ball with the Cardinals after being drafted. His jump in his first full season of professional baseball to 169 2/3 innings is well within the acceptable range of "jump" in innings thrown.
2013 is a much more difficult comparison. You see, Maness was a starter for all of those seasons, minus the last little bit of 2011 when he hit professional ball - starting a few games and relieving a few games that year. In 2013, he started his first 4 games in the minors and threw 25 innings. Since then, he threw 66 times out of the bullpen in St. Louis for 62 more innings in the regular season. He has already had 8 appearances in the post-season for 4 2/3 more innings. Oftentimes, managers will get a player like Maness (who usually pitches out of jams) warming a couple of times in a game - not always obviously. It is quite conceivable that Maness has warmed up in the bullpen over 100 times this year, however - leading to more pitches thrown than his body is accustomed to - thus tiring him out. We've seen the extra strain on Edward Mujica and Shelby Miller reduce them to being standbys in the bullpen this post-season.
While I'm hoping it is theory number one, just being a small sample size issue; I'm wondering if Seth Maness' arm has gone by the by as well.