Bill James, the stathead of all statheads, has a new book out called The Bill James Gold Mine 2009, in which he spews forth his usual stylings of statistical analysis and fascinating goodies.

Here are the some the highlights:

• Carlos Pena drew nine bases-loaded walks in 2008. To put that in perspective, that’s 50 per cent more than any hitter has had in a season over the past 20 years, with the only exception being D’Angelo Jimenez, who drew seven such walks in 2004. Pena, a a 46-HR man in 2007 who hit another 31 last year I can see, but D’Angelo Jimenez? Why the hell would anyone walk him with the bases loaded? In fact, what was he even doing up with bases loaded? Wouldn’t his manager have pinch-hit for him in that situation? Amazingly, Jimenez only had 17 bases loaded at bats that season, but he did seem to have a penchant for walking in 2004, drawing a career high 82 free passes.
• Grady Sizemore hit .202 on pulled ground balls in 2007 and he dipped to .172 last season. The reason? Teams are employing more infield shifts against Sizemore. He had a career high in homers in 2008, but hit 22 points lower than the career-best .290 he put up in 2006. If Sizemore is going to jack his batting average up to the point he will help fantasy owners, he’ll need to steer clear of the ground balls to the right side.
• The Florida Marlins made history last season when each of their regular infielders hit at least 25 home runs – a major league first. Shortstop Hanley Ramirez led the way with 33, while second baseman Dan Uggla and first baseman Mike Jacobs each jacked 32. Third baseman Jorge Cantu brought up the rear with 29 dingers, falling just one shy of giving the team a quartet of 30-homer infielders. Cantu started September like he planned to join them, smacking seven big flys in the first 14 games, but he failed to go yard over the final eight games.
• Met shortstop Jose Reyes was far away the major league leader by leading off 317 innings. He also led the majors by reaching base 118 times when leading off an inning. Can you please explain to me why Jerry Manuel considered shifting Reyes out of the lead-off slot? This dude is the best top-of-the-order hitter in baseball. You don’t mess with that.
• Apparently, Willie Harris – who again does not have a full-time role in 2009 – is one of the best defensive left fielders in the game. He played just 562 innings in left field last season, which is less than 40 per cent of the schedule, yet he was a +22, which means he made 22 plays that a LFer would not normally make. The major league leader among LFs was Carl Crawford, who was a +23. Harris was almost as good in 2007, when he recorded a +18 in 620 innings of work.
• The Seattle Mariners were the worst team in the AL in 2008, and were very close to scraping the bottom of the barrel in the entire majors. There were plenty of reasons why, but here’s a good one: they had a man on second base with no outs 116 times in 2008, but managed to score only 111 runs in those innings. No other major league team averaged less than a run per inning under those circumstances. The worst offenders? Adrian Beltre hit .216 with runners in scoring position. And he stuck around all season. At least the club had the sense to rid itself of Richie Sexson (.123) and Jose Vidro (.228) before they did too much damage.
• If the Royals are better this season – and I’m totally expecting them to make a big leap – how good is Joakim Soria going to be? He led all MLB relievers by recording 36 innings in which he retired the side in order. This dude is for real.

BY BILL GILBERT

Bill offers his take on the appropriate use of on-base percentage in measuring performance. Comments are welcome.‘

About 20 years ago, I recall asking a group of knowledgeable baseball friends what they thought the best single statistic was for measuring offensive performance. The consensus was that it was slugging percentage. If I posed the same question today to respected baseball analysts, I’m certain that the answer would be on-base percentage and they could cite studies to support their position.

The importance of on-base percentage in scoring runs is obvious. However, is it always the best way to evaluate a player’s performance? Consider the curious case of Morgan Ensberg. In 2005, Ensberg had a breakout year, batting .283 with 36 home runs, 101 RBI and an on-base percentage of .388. He was voted the Most Valuable Player on Houston’s National League Championship team and finished fourth in the voting for the National League MVP.

In 2006, he started out on an even stronger pace with nine home runs and 19 RBI in April. Among National League batters, only Albert Pujols had a better month. Ensberg finished the 2006 season with an on-base percentage of .396, an improvement over his strong showing in 2005. So he must have had a better year in 2006 than in 2005, right?

Not so fast. Let’s take a look at the other numbers.

In 2006, Ensberg batted .235 with 23 home runs and only 58 RBI. He began the season batting fourth in the lineup behind Lance Berkman and in front of Preston Wilson and Jason Lane. His primary job was to drive in runs, and with Berkman having an outstanding season, he had plenty of opportunities.

Ensberg’s performance tailed off sharply in May when he batted only .216 and was even worse in June. He was batting .174 for the month when he injured his right shoulder on June 9. Ensberg missed a week before returning to the lineup, but was obviously hampered by the shoulder injury and finally went on the disabled list on July 10.

Ensberg’s poor performance and injury prompted the Astros to trade away two prospects to Tampa Bay for third baseman Aubrey Huff. It also provided an opportunity for Mike Lamb to play third base. When Ensberg returned from the disabled list on August 1, he did not play well enough to regain his starting position and he played intermittently for the remainder of the season. In August and September, Ensberg had an on-base percentage well over .400, but had only four home runs and 14 RBI in 171 plate appearances, an unacceptable rate for a batter in the middle of the order.

Ensberg seemed reluctant to swing the bat when he came back, which may have been due to continued shoulder soreness. He did not hit with power and appeared to be working for walks which also resulted in a lot of strikeouts. Simply put, Ensberg did not provide the type of offensive production that the offensively-challenged Astros needed in the middle of the batting order.

With Ensberg’s failure as a run producer, the Astros needed to beef up the offense and may have overspent and mortgaged the future in signing free agent Carlos Lee to a six-year, $100-million contract. Another reason for the need for more run production was the failure of Lane to produce in 2006. Lane led all NL right fielders in home runs in 2005 with 26 while batting .267. However, in 2006, he hit just 15 home runs while batting only .201. Lane, like Ensberg, had a higher on-base percentage in 2006 than he did in 2005.

What can be learned from this development is that on-base percentage, while important, especially for hitters at the top of the batting order, can be much less important for hitters in the middle of the order who are expected to be run producers.

Bill Gilbert writes on a variety of baseball-related topics and is a frequent contributor to RotoRob.com.