The Cardinals and Phillies are playing the last game of their Division Series tomorrow, with each team’s ace (Chris Carpenter and Roy Halladay) taking the mound. The game—and thus the series—may very well be settled by which team’s ace pitches better. But it might just come down to which team’s manager has the audacity to sit his ace down on the bench.

One game this series has already been strongly influenced by a decision to pinch-hit (or not) by each manager—Cardinals starter Jaime Garcia struck out with runners on first and second to end the sixth inning in Game Three, then stayed in to allow a three-run homer to Phillies pinch-hitter Ben Francisco in the seventh.

I spend an awful lot of time talking about baseball data—what data we have, how we can tell if data is good or bad, what data we need to answer certain questions.

Here at BP we use a lot of baseball data, most of it either seasonal accounts (now from the Palmer database) or play-by-play data compiled by the fine, fine folks at Retrosheet. Up until now, we’ve had only scattered usage of one of the most exciting sources of data to come about in recent years—the PITCHf/x data collected by Sportvision for MLB Advanced Media’s Gameday product.

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I remember the first moment when I fully realized that I could die, and in fact could die very soon. I don’t think anyone ever forgets that sort of moment—at least, the ones who live to talk about it. Not at all coincidentally, this occurred only a few minutes after what I believe was the start of hostilities in the Iraq War.

It was March 20, 2003, and I was at a place called Camp Commando, which was an overly formal name for an otherwise-barren patch of desert in northern Kuwait. I was the most junior member of a small office for Marine Corps public affairs (in other words, media relations). There hadn’t been enough trailers shipped over from the US when we got to Kuwait at first, so we were working out of a trailer purchased locally and retrofit to our needs. It wasn’t a fancy job—the windows had been covered over with nothing more than sheets of cardboard to keep the sand and the heat at bay.

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As October gets closer and closer, baseball fans have some shopworn sentiments to trot out:

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It’s the end of an era for the Cubs. Tom Ricketts, public face of the Ricketts family trust that bought the team in 2009, announced this morning that general manager Jim Hendry had “stepped down,” which left out the little detail that he was given a bit of a shove first. It’s become increasingly clear that the Cubs have needed a new direction for many years, and now they certainly are going in a new direction.

Nobody will accuse Hendry of being the world’s greatest GM, but he is perhaps taking more than his fair share of the blame from Cubs fans. Ricketts was careful to avoid turning Hendry into a scapegoat, praising him for his work and dedication. Today’s press conference shed some new light on the baffling behavior of the Cubs this past month; Hendry was informed of the decision to move on back on the 22^nd of July, just over a week before the trade deadline. He was asked to stay on to finish signing the team’s amateur draft picks, and he agreed. This explains the inactivity of a man nicknamed “Trader Jim” for his wheeling and dealing ways; taking a laissez faire approach gives his successor more freedom.

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The Cardinals and the Brewers are in the midst of a drawn-out battle to determine the winner of the NL Central, and with two-thirds of the schedule complete, the Brewers have finally elbowed their way into the lead with a 67.9 percent chance of winning the division, according to our Playoff Odds Report at Baseball Prospectus. Looking at the standings, which show the two teams separated by a mere 3.5 games, one can’t help but wonder—what would the division look like if Albert Pujols had played up to expectations this season?

It’s not as though Pujols has been bad—with 3.6 Wins Above Replacement Player so far this season, he’s already produced more than a typical starter would in a full season, and the fourth-highest figure among all primary first basemen. However, prorated out over a full season of games, that’s only a 5.3 WARP pace, nearly three games short of the 8.1 WARP Pujols was projected to earn by PECOTA before the season began. (And lest we think that PECOTA was a touch optimistic, Pujols’ average WARP over the past three seasons was 9.6.)

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As the non-waiver trade deadline approaches, there’s been a flurry of activity. But how much of a difference do these deadline deals really make? Can a key acquisition make the difference between playing in October and staying home?

We can measure this by looking at a stat called Wins Above Replacement Player, which measures how well a player performs compared to a hypothetical backup. When evaluating in-season moves, this is a good, but not perfect, proxy for a team’s available assets. It’s a composite of the options available to a typical team, which can ignore some finer points of roster management. Most teams, after all, make deadline deals to shore up weaknesses, not strengths. So comparison to backups, rather than an average player, is a better model for the reality most GMs face.

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Recently, there has been a lot of digital ink spilled about ERA estimators—statistics that take a variety of inputs and come up with a pitcher’s expected ERA given those inputs. Swing a cat around a room, and you’ll find yourself with a dozen of the things, as well as a very agitated cat. Among those is SIERA, which has lately migrated from here to Fangraphs.com in a new form, one more complex but not necessarily more accurate. We have offered SIERA for roughly 18 months, but have had a difficult time convincing anyone, be they our readers, other practitioners of sabermetrics, or our own authors, that SIERA was a significant improvement on other ERA estimators.

The logical question was whether or not we were failing to do the job of explaining why SIERA was more useful than other stats, or if we were simply being stubborn in continuing to offer it instead of simpler, more widely adopted stats. The answer depends on knowing what the purpose of an ERA estimator is. When evaluating a pitcher’s performance, there are three questions we can ask that can be addressed by statistics: How well he has pitched, how he accomplished what he’s done, and how he will do in the future. The first can be answered by Fair RA (FRA), the third by rest-of-season PECOTA. The second can be addressed by an ERA estimator like SIERA, but not necessarily SIERA itself, which boasts greater complexity than more established ERA estimators such as FIP but can only claim incremental gains in accuracy.

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Grantland, Bill Simmons’s vanity project, has taken some space since its launch to discuss sabermetrics. My takeaway so far is that nobody involved with Grantland knows a thing about the subject.

A few weeks ago, Grantland published Bill Barnwell’s guide to the new Moneyball, which was mostly a rehash of the old Moneyball alongside some factual errors. (For instance, Barnwell claims the sort of data required to do defensive metrics like UZR and Plus/Minus “didn’t really exist” when Moneyball was written. This requires ignoring that both of those metrics predate the publication of Moneyball. It also requires ignoring the fact that STATS, Inc. was collecting this data as far back as the 1980s. It also requires ignoring the fact that Moneyball talks about how STATS, Inc. was collecting this data in the 1980s, and the fact that Moneyball also talks at length about how the A’s first bought and then built such defensive metrics for their own use. After having this pointed out to him on Twitter, Barnwell allowed that he could have “phrased it better,” which makes it seem like being totally wrong about the facts is the same thing as being misunderstood.)

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Before we can talk about Derek Jeter (and yes, I think there’s still something to say about Derek Jeter that you haven’t already heard this season), we should probably clarify which Derek Jeter we’re talking about. There really are two Derek Jeters—the one who exists in fact, and the one who exists in myth.

The actual Derek Jeter is interesting enough as a player that one wonders why the myth was necessary—always an exceptional hitter, Jeter has always been a player who could’ve had a job on any team in the league. He will go into the Hall of Fame on the first ballot, and nobody will bat an eye. Then there’s the Captain—the athlete whom ad agencies consider akin to Tiger Woods and Roger Federer. The player so exceptional that he can displace a generational talent like Alex Rodriguez from his natural position.

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The Minnesota Twins have the somewhat unique distinction of being left wanting by Francisco Liriano’s performance—not just his early-season struggles, but his body of work as a pitcher. Manager Ron Gardenire told reporters:

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As the season began, Fernando Rodney’s hold on the Angels’ closer job was believed to be tenuous. Other than possessing the “proven closer” label, there wasn’t much about Rodney to recommend him for the role. His “success” as a closer, such as it was, was more a testament to how overrated the role is, not his own ability to pitch.

Despite those concerns, few would have expected him to surrender the title as early as he did: Rodney was removed from the closer role on Tuesday, after just two outings and one blown save. What was it about the one-and-a-third innings Rodney had pitched so far this year that wasn’t already apparent from the previous 398 innings under his belt? Sure, the most recent innings were worse, but anyone can pitch that poorly in less than two innings. A more impressive sign of mediocrity is being able to pitch a hairsbreadth away from replacement level for eight seasons, which Rodney had already accomplished.

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