Run saved a run earned for Red Sox

Imagine the buzz if the Red Sox had added 87 runs of offense this offseason. The excitement would be palpable, if they had put together the club's most potent offense since Ted Williams roamed the outfield.

But rather than add 87 runs of offense this offseason, Boston opted to save 87 runs on defense. At least that's what Baseball Info Solutions projects.

In Mike Cameron and Adrian Beltre, the Red Sox brought in two former Gold Glovers to anchor the defensive improvement prioritized by the team in the offseason. Meanwhile, Marco Scutaro is expected to provide much-needed stability at shortstop.

No one would dispute that better fielders make for a better team. But just how many more games will the Red Sox win courtesy of their defense?

To make that kind of projection, errors and fielding percentage just won't do. Neither properly takes into account how many balls a fielder gets to -- his range. Nor do those stats factor in the situation. An RBI rewards a hitter who drives in baserunners. Otherwise, it would just go down as a hit. So if you are going to credit a hitter for driving in a run, shouldn't you do the same for a fielder for saving a run?

Not all fielding plays are created equal, but you wouldn't know that from the standard fielding statistics. Shouldn't we differentiate fielding plays based on situation and difficulty?

Well, Baseball Info Solutions has attempted to do just that.

Defensive Runs Saved is a simple name for an intricately tracked statistic. Essentially, it takes a massive database of defensive information and simplifies it into a single number estimating a player's defensive value.

Every ball in play is charted, and the field is divided into vectors to determine the frequency with which each play gets made. Other components come into play, such as throwing arm and bunt defense. The number of outs and runners on base are also taken into account to determine the probability that a run would score in a given situation.

Got all that? You can find much more on the math in John Dewan's Fielding Bible. But for now, all you need to know is the number reflects how many runs a player saved or cost his team with his defense compared to an average player.

In 2009, the Red Sox defense was a minus-52 in defensive runs saved, meaning that it cost the team 52 more runs than an average defense would have. That's as bad as it sounds. In fact, only the Royals (minus-62) were worse. Among the primary offenders? Mike Lowell (minus-18), Julio Lugo (minus-17), Jacoby Ellsbury (minus-9) and Jason Bay (minus-2). It's no coincidence that all four of their positions were overhauled in the offseason, with Ellsbury's move to left field part of that equation.

Ellsbury may be the most puzzling name on that list given his penchant for highlight catches. But consider this fascinating note courtesy of Baseball Info Solutions (not only does it show the depth of the defensive analysis, but also a potential weakness in Ellsbury's game that may otherwise go unnoticed): Last season, Ellsbury had nine plays that were categorized as "failure to anticipate the wall." Picture the ball hitting off the wall past the fielder, who has to retreat to get to it. This happened to Ellsbury more than any other fielder last season.

Incoming are players who shine based on the runs saved metric. Cameron (plus-3) and Scutaro (plus-12) were brought in to solidify the defense up the middle. Ellsbury provides reason for optimism in left field based on data presented by Bill James in "The Fielding Bible -- Volume II." According to James, Ellsbury played 346 innings in left field in 2008, during which time he made no errors and only two misplays. That was "by far the best mistake rate of any left fielder playing 125 or more innings."

However, the true defensive gem is Beltre, whom the Fielding Bible deemed the best third baseman in the majors in two of the past four seasons. Last season, despite battling injuries, he finished with 21 runs saved, third among third basemen. By the same metric, he's projected to be the sixth-most-valuable defensive player in the majors in 2010.

So where do these defensive improvements put the 2010 Red Sox?

Last week on ESPN Insider's TMI blog, Baseball Info Solutions posted various projections for 2010. The Red Sox defense is expected to save 35 runs. That's not quite the best in baseball (that would be the Mariners at an astounding 103 runs saved, more than double any other team), but it puts the Red Sox among the elite.

It's an astounding projection for a team with the second-worst defense in the league last year. An increase of 87 runs saved is by far the biggest projected improvement in baseball. The A's are next with a projected increase of 49 runs saved.

So what does an improvement of 87 runs saved mean in the win column? Baseball Info Solutions believes that every 10 runs saved is worth a win. That means the Red Sox are projected to improve by about nine wins based on their defense alone.

Assuming the projection is correct, perhaps other recent examples of massive defensive improvement provide a window into the upcoming season. According to BillJamesOnline.net, only two teams had an improvement of at least 85 runs saved over the past two seasons: the 2008 Rays and the 2009 Mariners.

For those concerned about the Red Sox offense, consider this: Both the 2008 Rays and 2009 Mariners saw massive win improvements despite a decrease in runs scored. How did they do it? Runs saved played a huge role.

The 2008 Rays improved by 85 runs saved, going from the worst defense in the majors to the fourth-best in the AL. Thanks to defense (namely Evan Longoria) and improved pitching, they allowed 273 fewer runs, leading to a 31-win improvement.

Last year, the Mariners similarly improved by 24 wins despite scoring 31 fewer runs. They improved by 94 runs saved, going from an average defense to the best in the majors. Center fielder Franklin Gutierrez, acquired in the offseason, ranked as the best defensive player in the majors according to runs saved.

Both teams achieved dramatic improvement largely thanks to offseason acquisitions that zeroed in on defense. The same could hold true for Boston. It may not show up in the box score, but in the end, a run saved is a run earned.

Jeremy Lundblad is a researcher with ESPN Stats & Information. He provides statistical analysis for ESPNBoston.com.