While looking toward the future with our comprehensive slate of current content, we'd also like to recognize our rich past by drawing upon our extensive online archive of work dating back to 1997. In an effort to highlight the best of what's gone before, we'll be bringing you a weekly blast from BP's past, introducing or re-introducing you to some of the most informative and entertaining authors who have passed through our virtual halls. If you have fond recollections of a BP piece that you'd like to nominate for re-exposure to a wider audience, send us your suggestion.

Over 11 years after their publication in Baseball Prospectus 2000, how many of Keith's questions for a new millenium have we already set to rest?

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While looking toward the future with our comprehensive slate of current content, we'd also like to recognize our rich past by drawing upon our extensive online archive of work dating back to 1997. In an effort to highlight the best of what's gone before, we'll be bringing you a weekly blast from BP's past, introducing or re-introducing you to some of the most informative and entertaining authors who have passed through our virtual halls. If you have fond recollections of a BP piece that you'd like to nominate for re-exposure to a wider audience, send us your suggestion.

With our depth charts and team projections up and running, now seems like a fitting time to repeat Keith's caveats about the inherent limitations of such worthwhile exercises, nearly six years after his words originally ran on March 24, 2005.

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Baseball Prospectus has, since its inception, been dedicated to the concept that that there are better ways for major league baseball teams to make decisions. Augmenting conventional, scouting-based reports with objective evidence gathered through analysis of the statistical record can help a team gain a competitive edge. This philosophy, long advocated by BP, reached a critical mass of awareness through Michael Lewis' bestseller Moneyball, and initiated a wave of change that has swept across the ranks of professional baseball. It has even carried some BPers into positions with major league teams. That trend continues today.

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Will talks with Keith about Boston's chances in the Red Sox Hope and Faith edition of Baseball Prospectus Radio. Click to download the mp3.

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\nMathematically, leverage is based on the win expectancy work done by Keith Woolner in BP 2005, and is defined as the change in the probability of winning the game from scoring (or allowing) one additional run in the current game situation divided by the change in probability from scoring\n(or allowing) one run at the start of the game.'; xxxpxxxxx1160407218_18 = 'Adjusted Pitcher Wins. Thorn and Palmers method for calculating a starters value in wins. Included for comparison with SNVA. APW values here calculated using runs instead of earned runs.'; xxxpxxxxx1160407218_19 = 'Support Neutral Lineup-adjusted Value Added (SNVA adjusted for the MLVr of batters faced) per game pitched.'; xxxpxxxxx1160407218_20 = 'The number of double play opportunities (defined as less than two outs with runner(s) on first, first and second, or first second and third).'; xxxpxxxxx1160407218_21 = 'The percentage of double play opportunities turned into actual double plays by a pitcher or hitter.'; xxxpxxxxx1160407218_22 = 'Winning percentage. For teams, Win% is determined by dividing wins by games played. For pitchers, Win% is determined by dividing wins by total decisions. '; xxxpxxxxx1160407218_23 = 'Expected winning percentage for the pitcher, based on how often\na pitcher with the same innings pitched and runs allowed in each individual\ngame earned a win or loss historically in the modern era (1972-present).'; xxxpxxxxx1160407218_24 = 'Attrition Rate is the percent chance that a hitters plate appearances or a pitchers opposing batters faced will decrease by at least 50% relative to his Baseline playing time forecast. Although it is generally a good indicator of the risk of injury, Attrition Rate will also capture seasons in which his playing time decreases due to poor performance or managerial decisions. '; xxxpxxxxx1160407218_25 = 'Batting average (hitters) or batting average allowed (pitchers).'; xxxpxxxxx1160407218_26 = 'Average number of pitches per start.'; xxxpxxxxx1160407218_27 = 'Average Pitcher Abuse Points per game started.'; xxxpxxxxx1160407218_28 = 'Singles or singles allowed.'; xxxpxxxxx1160407218_29 = 'Batting average; hits divided by at-bats.'; xxxpxxxxx1160407218_30 = 'Percentage of pitches thrown for balls.'; xxxpxxxxx1160407218_31 = 'The Baseline forecast, although it does not appear here, is a crucial intermediate step in creating a players forecast. The Baseline developed based on the players previous three seasons of performance. Both major league and (translated) minor league performances are considered.

The Baseline forecast is also significant in that it attempts to remove luck from a forecast line. For example, a player who hit .310, but with a poor batting eye and unimpressive speed indicators, is probably not really a .310 hitter. Its more likely that hes a .290 hitter who had a few balls bounce his way, and the Baseline attempts to correct for this.

\nSimilarly, a pitcher with an unusually low EqHR9 rate, but a high flyball rate, is likely to have achieved the low EqHR9 partly as a result of luck. In addition, the Baseline corrects for large disparities between a pitchers ERA and his PERA, and an unusually high or low hit rate on balls in play, which are highly subject to luck. '; xxxpxxxxx1160407218_32 = 'Approximate number of batting outs made while playing this position.'; xxxpxxxxx1160407218_33 = 'Batting average; hits divided by at-bats. In PECOTA, Batting Average is one of five primary production metrics used in identifying a hitters comparables. It is defined as H/AB. '; xxxpxxxxx1160407218_34 = 'Bases on Balls, or bases on balls allowed.'; xxxpxxxxx1160407218_35 = 'Bases on balls allowed per 9 innings pitched.'; xxxpxxxxx1160407218_36 = 'Batters faced pitching.'; xxxpxxxxx1160407218_37 = 'Balks. Not recorded 1876-1880.'; xxxpxxxxx1160407218_38 = 'Batting Runs Above Replacement. The number of runs better than a hitter with a .230 EQA and the same number of outs; EQR - 5 * OUT * .230^2.5.'; xxxpxxxxx1160407218_39 = 'Batting runs above a replacement at the same position. A replacement position player is one with an EQA equal to (230/260) times the average EqA for that position.'; xxxpxxxxx1160407218_40 = 'Breakout Rate is the percent chance that a hitters EqR/27 or a pitchers EqERA will improve by at least 20% relative to the weighted average of his EqR/27 in his three previous seasons of performance. High breakout rates are indicative of upside risk.

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For those of you who haven't played around with the new reporting system, I highly recommend it. Almost all of the currently available standard stat reports are, in fact, using the new system.

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I was recently wondering about the how the game has changed, even over that relatively short span of time. One of the things you commonly hear about "the old days" is how pitchers threw so many more innings, presumably because they were tougher, less coddled, or generated more testoserone. From a sabermetric perspective, the arguments against that usually include how selective memory focuses on the exceptional pitchers, not the dozens or hundreds of pitchers who were forced to quit early due to a dead arm, or how pitchers nowadays have to expend a full effort on every pitch, unlike in Christy Mathewson's day where pitchers could coast until crucial moments of the game, or how even the greats of a generation ago were pitching significantly fewer innings than their predecessors, and how this trend has been almost constant since the inception of professional baseball. While there is truth in all of these arguments, I was interested in a different tack. What if plate appearances themselves require more pitches in the modern game than in years past? If batters have gotten more selective, or better at fouling off pitches, then 30 batters faced in 1950 may have taken less pitcher's work than 30 batters in 2005 would have.

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Interestingly, only 19 pitchers had a "choke" during 2005, and only one pitcher had more than one--Chad Bradford, with just two chokes. On July 26th, he came into a 5-1 game with two runners on base, and lost the lead on an Aubrey Huff grand slam. Then on August 9th, he came in with the bases loaded and a 7-3 lead, and gave up two hits, an intentional walk, and two run-scoring groundouts, and left with the game 7-7 and runners still on second and third.

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Though there are examples prior to the 1990's--Tim McCarver catching Steve Carlton almost exclusively, for example--the phenomenon of the personal catcher has become more prevalent in the the past 15 years. Greg Maddux' preference of Eddie Perez (also Paul Bako or Henry Blanco in later seasons) over regular catcher Javy Lopez is well documented. John Flaherty was Randy Johnson's personal catcher in 2005. The unique demands of catching the knuckleball has meant that Mirabelli has worked with Tim Wakefield for the past several seasons, giving Jason Varitek the night off.

Giving the primary catcher periodic rest is one of supposed benefits of this arrangement. With the personal catcher playing every 5th day when his pitcher's turn in the rotation came up, it created a pattern of 25-30 games per year the regular catcher would have off. This rest, in theory, would help the regular catcher from getting worn down over the course of a long season, remaining fresh enough even in September to contribute offensively. It is this question that interests me today--do personal catchers provide a measurable boost to their primary counterparts by allowing them periodic rest? Does the fact that Tim Wakefield has Josh Bard (and previously, Doug Mirabelli) as a personal catcher help Jason Varitek stay productive in September?

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Baseball Prospectus to the rescue. Here's a quick and dirty way you can approximate the expected number of runs given the bases that are occupied and the number of outs. We'll use an example to demonstrate--runners on first and third with one out:

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With apologies to Edgar Allan Poe

Once upon a midnight dreary, while I waited, weak and weary
For the ballgames to be finished on the distant western shore.
While I started nearly dozing, with my eyes so slightly closing
I flicked on the tube, supposing to catch the highlights, one or more
Grabbed the clicker, settled in, and tuned to channel thirty-four,
A certain channel I adore.

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