Sixth inning is game's big test

When an opponent starts to rally in the middle innings, Braves manager Fredi Gonzalez will stand in the corner of the dugout, planning with pitching coach Roger McDowell how to find a bridge to their dominant late-game relievers, Jonny Venters, Eric O'Flaherty and Craig Kimbrel.

"There are times I've been here with Roger, when that sixth inning gets a little hairy," Gonzalez said, "and I would say, 'Here we go again. This is the spot.'"

Atlanta is, after all, 76-4 when it holds a lead at the start of the seventh inning -- at which point the aforementioned trio tends to take over -- but has given up more runs in the sixth than in any other inning.

Getting a pitcher through that sixth inning unscathed is a league-wide issue, and it's one that will take on increased scrutiny in the playoffs, when starters are kept on a tighter leash, and a reliever who can effectively pitch multiple innings is of great importance. And with off-days built into the schedule, mangers can be more liberal with their bullpen usage.

Last year, for example, the Rangers' Alexi Ogando was a starter who pitched out of the bullpen in the playoffs. Seven times he pitched in the sixth for Texas and, though he gave up three runs in 16-7 drubbing by the Cardinals in World Series Game 3, he otherwise didn't allow a run of his own while getting 14 high-leverage outs in the sixth. He allowed a pair of inherited runners to score but also notched a hold and two wins, the latter because of work in tie games.

The Cardinals may have their own version of Ogando this year in Lance Lynn, an All-Star for his first-half success but who has made a half-dozen relief appearances in the second half. If St. Louis can hang on to its second wild card spot -- it has a two-game lead over the Dodgers with three to play -- Lynn may find himself pitching crucial innings out of the bullpen now that Chris Carpenter has returned to join Kyle Lohse, Adam Wainwright and Jaime Garcia in the rotation.

So while there will be much talk this fall of the swing states that will decide the presidential election, so too will baseball's ultimate winner be decided in part by which team is most effective in the sixth inning, the game's swing inning.

Most years the sixth is annually one of the game's highest two scoring innings, along with the first. This year it actually ranks third (behind the first and fourth), but the sixth is the important "action inning" -- if a pitcher gets into trouble in those earlier two frames, a manager is more likely to let him work through the jam. In the sixth, however, the manager often faces a tough decision.

As would be expected, a club's winning percentage improves with each completed inning it holds a lead, but the jump from the end of the fifth (83.9 percent) to the end of the sixth (88.1 percent) is the largest increase in win probability.

That the sixth inning is one of the two regularly problematic frames for a starter, along with the first inning, is well known enough that a couple of pitchers, Kansas City's Luke Hochevar and Arizona's Ian Kennedy, call them "The Terrible Twos."

Kennedy, whose Diamondbacks conquered the sixth inning last year by scoring the most runs but allowing the third-fewest, said he learned the term from Hochevar when they played for Team USA in college.

"Especially at this level and the quality hitters that you're facing, [a big inning] can happen in any inning," Hochevar said, "but it does happen in those two the majority of the time."

Indeed, in the 18 seasons of the wild card era, the average starting pitcher has lasted less than six innings in 16 of them, and the first and sixth are the two highest-scoring innings:

The reasoning behind the all the runs in the first inning is obvious: It's the only inning when a manager can be sure to stack his order with his best hitters. That's the predominant cause, though often pitchers may need an inning to settle into a game.

Why the sixth is such a big offensive inning is more complicated, and its importance is growing: Since 2006 the sixth has been one of the two highest-scoring innings five out of seven years.

But it is hardly a new development. Since 1974, the first year for which Baseball-Reference.com has complete play-by-play data, the sixth inning has ranked in the top-three for runs scored in 30 of 39 seasons.

Among the biggest reasons the sixth so often shapes up as a game-changing crossroads:

• Tiring starter or long reliever

Every pitcher, Rays manager Joe Maddon said, has his own "Waterloo mark," after which his effectiveness declines.

"It pretty much remains consistent with each guy," Maddon said. "They all like the idea of the quality start" -- which requires six full innings of work and three or fewer earned runs allowed -- "and if you manage from the perspective of trying to get your guys quality starts, you're going to end up losing a lot of games."

With a league-wide rate of 16.3 pitches per inning, on average a starter has thrown 82 pitches entering the sixth inning and will be flirting dangerously close with the 100-pitch threshold by the end of the inning. According to STATS LLC, an opponent's OPS is highest against a pitcher in between 76 and 90 pitches, with a .772 mark that suggests every hitter is suggests every hitter approximates the production of the Twins' Justin Morneau.

"When the starter gets fatigued, that's going to happen," Brewers manager Ron Roenicke said. "The fifth, sixth and sometimes the seventh, those are the hardest innings to manage because you know the starter is stressed, you're in a part of the ballgame when you're thinking about taking him out or leaving him in for one more inning. You know he's a little fatigued, but maybe you want to save your bullpen. By doing that you're going to get in trouble."

Dependable starters and aggressive bullpen usage can make the difference. The Rays have allowed the fewest runs in the sixth of any team in baseball. That's largely a credit to their starters, but also to frequent appearances in that inning by J.P. Howell, Wade Davis, Burke Badenhop and Jake McGee, each of whom has made at least 12 appearances in the sixth.

"So that's when you talk about the middle-inning closer," Maddon said. "You have to really shut the game down there and hopefully keep the positive number on your side or at least the tie."

The quality of a reliever in the sixth is also an issue. Almost universally, a team tries to save its best relievers for the game's final three innings, exposing that sixth inning to a lower-quality pitcher. One crude measurement to illustrate this is to compare the league-wide percentage of inherited runners who score when a reliever enters in the first six innings of a game (31.4 percent) against the rate when a reliever enters in the seventh or later (27.8 percent).

"That bridge to the seventh guy is one of the most underappreciated [positions] or glaring weaknesses on a team," Red Sox reliever Craig Breslow said. "If you can put together three or four guys who are capable of pitching at the back end but just aren't because of circumstance, you probably have your best chance."

• Third at bat vs. starting pitcher

Even if the starter isn't tiring, he faces a difficult task in the sixth, navigating a lineup for the third time. By the third plate appearance, though, "you've seen every pitch he has," Nationals third baseman Ryan Zimmerman said. "That's half the battle. That's why you see so many people take a lot in their first at bat, trying to get to those other pitches just to see them. As a hitter, at least for me, I want to try and see all their pitches so later in the game, if I come up in a big spot, I know what to expect and know that I've seen it. It makes you feel more comfortable."

A hitter's OPS is 66 points higher in his third at bat against a pitcher than in his first.

• Middle of the lineup batting

It's frequently not just that a pitcher is facing the lineup for the third time, but who he's facing. Often, by the sixth inning, he's trying to navigate a lineup's best hitters. The reason is simple math, based on the average number of batters faced each game and evident over the course of a long season.

Rockies catching coach Jerry Weinstein points out that there are 4.2 hitters in every inning, and thus, "If you get to the sixth inning, you're hitting 21 or 22 -- so you're hitting that 2, 3, 4, 5, 6 part of the lineup."

Indeed, at 4.2 hitters per inning over five innings equates to 21 batters faced, which is two full laps through the nine-man batting order, plus three additional outs. That would put the No. 4 hitter batting for a third time in the sixth.

There is strong anecdotal evidence to support a spike in likelihood of the No. 4 hitter batting in the sixth inning. Take the Tigers' Prince Fielder, for example. He has been batting fourth for every single plate appearance for two different teams in two different leagues in 2011 and '12. In 2011 with the Brewers, he batted 68 times in the fifth inning, 84 times in the sixth and 69 times in the seventh. So far in 2012, those numbers are 65-90-70.

Similarly, the Phillies' Ryan Howard has only started games as the No. 4 hitter the last two years, and his combined numbers are 89 plate appearances in the fifth, 116 in the sixth and 74 in the seventh. And the Rockies' Troy Tulowitzki has made 180 of his 187 starts as the clean-up hitter and has a plate appearance spread of 80-97-81.

Getting through that sixth inning has been a challenge for all teams, even playoff-bound clubs like the Braves. Atlanta's Kris Medlen has been a dominant starter the past two months, but had trouble earlier in the season relieving in the sixth, allowing six earned runs in 11 2/3 innings in that frame while working out of the bullpen.

"When we get six, seven innings from one of our starters, we're nearly unbeatable," third baseman Chipper Jones said. "That is our formula. We make no bones about it. It's a race to the end of the sixth, end of the seventh, for us."

Finishing that race with a lead is the hard part -- and doing so may determine who's still standing at the end of October.