All week, we've been ranking Major League Baseball's top 10 teams in the four major areas. On Monday, it was the rotations; on Tuesday, the bullpens; on Wednesday, the lineups. And now, we've come to the most problematic part of the program.

Defense is the most difficult element of the game to quantify and the easiest to overlook. Spectacular plays have a way of masking an otherwise average effort. Gold Gloves are given out largely on the basis of reputation, and, in some cases, on the might of offensive production, no matter the intentions of the honor. And for the most part, we only notice great team defense when it's not present.

So in order to rank the top 10 defenses in the game, entering 2012, I've consulted several defensive metrics -- most notably, Baseball Prospectus' team defensive efficiency rankings, Baseball Info Solutions' defensive runs saved and Fangraphs.com's Ultimate Zone Rating/150 games at each position from 2011 -- to try to come to some consensus on which teams turn the most balls put in play into outs, plain and simple.

Here's the top 10, hopefully sans errors:

10. Royals: Keep an eye on this club. The Royals have one of the best defensive shortstops in the game in Alcides Escobar, another plus defender in left in Alex Gordon, a tremendous arm in right in Jeff Francoeur and the speedy Lorenzo Cain in center. Salvador Perez is expected to be a plus defender behind the dish. The right side of the infield is very much a work in progress, as second baseman Johnny Giavotella showed obvious defensive shortcomings in his first exposure to the bigs, and UZR does not give a favorable rating to first baseman Eric Hosmer. All in all, though, it's reasonable to expect this to be a sound defensive unit in 2012.

9. Mariners: The simple truth is that if you're going to have as anemic an offense as the Mariners possess, you'd better have pitching and defense. Seattle ranked eighth on the park-adjusted defensive efficiency scale and a respectable 13th in defensive runs saved last year. Brendan Ryan and Dustin Ackley combined for the second-most defensive runs saved of any shortstop/second base combo in the Majors, trailing only Elvis Andrus and Ian Kinsler of Texas. In center field, Franklin Gutierrez is as dynamic a defender as there is. He ranked second in UZR/150 among center fielders. Strength up the middle goes a long way, though the Mariners are lacking in defensive help behind the plate. Jesus Montero won't help them there, but at least he'll help the offense.

8. Red Sox: The right side of Boston's infield is as good as it gets. Adrian Gonzalez ranked first in UZR/150 among first basemen, while Dustin Pedroia ranked second at second. The shortstop situation is very much uncertain, though Nick Punto provides above-average defense when healthy. Kevin Youkilis has been known to sacrifice his body at the hot corner, and, in a related development, has averaged just 119 games played over the past three years. That's a concern. In the outfield, Carl Crawford's plus defense is wasted in Fenway's tiny left-field terrain (and, actually, UZR/150 had him as a below-average defender last year), but Jacoby Ellsbury ranked third among American League center fielders. Both Jarrod Saltalamacchia and Kelly Shoppach are plus defenders behind the plate.

7. Dodgers: One bright spot to an overall frustrating 2011 was the defense, which committed the fifth-fewest errors in the Majors and ranked seventh on the park-adjusted efficiency scale. Mark Ellis will take over the everyday second-base duties, and he has a reputation as a strong defender. Matt Kemp led all center fielders in outfield assists with 11, while contributing nine total zone runs above average. James Loney profiled as the second-best defender among National League first basemen, behind the Reds' Joey Votto. The Dodgers should be solid behind the plate with A.J. Ellis and Matt Treanor.

6. Giants: The Giants were sixth in defensive efficiency and eighth in defensive runs saved last season. Pablo Sandoval has developed into an elite defender at third, ranking second in UZR/150 at that position last year. San Francisco has sacrificed some defense by adding Melky Cabrera to its outfield. But in the infield, if Brandon Crawford shows enough at the plate to become the regular at shortstop, the Giants will have a defensive gem at a premium position, paired with the solid Freddy Sanchez at second. Beyond that, Aubrey Huff is a plus defender at first and so is Brandon Belt, who will push Huff for playing time. Behind the plate, a full season of Buster Posey should be a boon to the defense.

5. D-backs: Arizona had arguably the best defensive outfield in baseball last year, with Gerardo Parra in left, Justin Upton in right and Chris Young in center. Each of those three guys ranked in the top eight at his position on the UZR/150 scale. The D-backs altered their defensive outlook by acquiring Jason Kubel to become the regular in left, as he's certainly no Gold Glover. But they still have a strong defensive cast. Third baseman Ryan Roberts and second baseman Aaron Hill are both above-average defenders, and getting Stephen Drew back at shortstop at some point this season will be a big help. To top it off, Miguel Montero had the third-most total zone runs saved among Major League catchers last year.

4. Rangers: Here's an example of the advanced metrics running counter to the common ones. Baseball Prospectus had the Rangers ranked second in defensive efficiency and fourth in park-adjusted defensive efficiency, and Baseball Info Solutions had them fourth in defensive runs saved, even though Texas made 114 errors last season -- the seventh most in the Majors. We'll side with the advanced stats and include the Rangers here. They get elite defense at second base and third from Kinsler and Adrian Beltre, each of whom ranked in the top three in UZR/150 at his position, and Andrus ranked in the top 10 at short. Josh Hamilton is a plus defender in left, and Mike Napoli was one of the highest-rated defensive catchers in the Majors, ranking eighth in total zone runs.

3. Reds: Cincinnati checked in with the third-highest ranking in regular and park-adjusted defensive efficiency, and it made the seventh-fewest errors in the Majors. Votto is not a now-annual NL MVP Award candidate solely because of his bat. He was the best defender at first in the NL, according to UZR/150. Brandon Phillips had the same ranking among NL second basemen. When healthy (and he wasn't last year), Scott Rolen is one of the game's top defenders at the hot corner. Shortstop is a question, as rookie Zack Cozart inherits the role. In the outfield, one wonders whether to trust the metrics or the eyes, for Drew Stubbs and Jay Bruce both appear to play their positions quite well but were actually given negative marks in UZR. Regardless, defense is clearly a point of emphasis with the Reds.

2. Angels: Defense has been a hallmark of the Mike Scioscia era, and that won't change in 2012. The Angels obviously bolstered their lineup when they brought in Albert Pujols, but they didn't sacrifice anything from a defensive perspective. Pujols is a strong defender at first (he's won five of the last six Fielding Bible awards at that spot). It remains to be seen how the Halos handle third base, where Alberto Callaspo was a solid defender last year. If Mark Trumbo moves there, it could hurt the defense. But up the middle, the Angels get a passing grade at short with Erick Aybar, and they have one of the best defensive second basemen in the game in Howie Kendrick. In the outfield, Peter Bourjos is emerging as an elite defensive center fielder, and Mike Trout also profiles as a strong option in left.

1. Rays: Baseball Prospectus ranked Tampa Bay first in both defensive efficiency and park-adjusted defensive efficiency last season. In fact, BP considered it the fourth-best defensive season ever. The Rays also committed the fewest errors of any team in the Majors. Their shortstop job, which will go to either Sean Rodriguez or Reid Brignac, is currently unsettled, but third baseman Evan Longoria and second baseman Ben Zobrist ranked fourth and fifth, respectively, at their position in UZR/150. And though plus defender Casey Kotchman is gone from first base, the Rays brought back Carlos Pena, who ranked 11th in UZR/150 with the Cubs last year. In the outfield, B.J. Upton, Matt Joyce and Desmond Jennings are all plus defenders, and don't forget "Super" Sam Fuld in the fourth outfield spot. Jose Molina takes over the starting catching duties and is considered a strong defender. It all adds up to the best defense in the game.

Honorable mention: The Phillies made the second-fewest errors last year, but they actually rated among the worst teams in baseball in defensive runs saved. Chase Utley, Jimmy Rollins and Placido Polanco are plus defenders when healthy, but injuries have plagued them and age is creeping up. ... The Nationals should be sound defensively, though it will be interesting to see how Jayson Werth fares in center once Bryce Harper arrives. ... Anecdotally, the Padres were disappointed with their defense in 2011. Statistically, they ranked second in park-adjusted defensive efficiency and fifth in defensive runs saved. They have, however, added two shaky defenders this offseason in left fielder Carlos Quentin and first baseman Yonder Alonso. ... The Braves rated favorably on the defensive efficiency scale, but losing veteran Alex Gonzalez hurts the infield. ... The Brewers are going to attempt to account for the loss of Prince Fielder (and possible suspension of Ryan Braun) with an increased emphasis on run prevention, and the addition of Gonzalez should go a long way in that regard. ... The Indians might find themselves on this list by year's end, depending on the development of Lonnie Chisenhall at third and Jason Kipnis at second and the health of center fielder Grady Sizemore.