This is Part VI of our series ranking the best team units. Today we focus on the best defenses, according to club evaluators -- and out of all the various units we've ranked, picking the best defensive group proved the most difficult.
The Kansas City Royals have played in the World Series the past two years in no small part because of how exceptional they are on defense, and they are an example of the way the entire sport is trending. This winter, teams are spending more on defense (hello, Jason Heyward) and veering away from sluggers who are defensively challenged (like Chris Carter and Pedro Alvarez), and the Royals are the best current example of the idea that success can come through fielding a bunch of guys who make plays on defense.
On the other hand, defensive metrics suggest that in 2015, the Arizona Diamondbacks were MLB's best glovemen -- and according to the defensive runs saved (DRS) statistic, it wasn't even close.
Team leaders in defensive runs saved, 2015
1. Arizona Diamondbacks 71 DRS
2. Kansas City Royals 56
3. Miami Marlins 37
4. Houston Astros 30
5. San Francisco Giants 28
So which group should be No. 1? Presenting the top 10 defenses in MLB:
1. Kansas City Royals
Look, both Arizona and Kansas City are worthy of the No. 1 spot, and compelling arguments can be made for both. A couple of developments swung the top spot to the Royals, though. First of all, Kansas City was able to retain four-time Gold Glove-winning left fielder Alex Gordon with a four-year deal. Gordon is not as dominant defensively as he was a few years ago, when he was a shutdown corner outfielder in the way that Heyward is now, but he's still very good out there, still makes plays, still works relentlessly. It also appears that the speedy Jarrod Dyson is poised to get more playing time in the outfield than he has in recent seasons, and since he'll be alongside Gordon and Lorenzo Cain, a whole lot of balls driven into the gaps against K.C. will be run down. It's a good time to be a Kansas City pitcher.
Additionally, the Diamondbacks traded the versatile Ender Inciarte, a strong defender who was fourth in DRS among left fielders with 300-plus innings there in 2015 and second (behind Heyward) among right fielders, as part of the Shelby Miller deal, and now Yasmany Tomas figures to get the bulk of the playing time in right field, with David Peralta in left. The Diamondbacks believe that Tomas' defense is better than it's generally thought to be and will improve as he gets more experience, but he posted a minus-8 DRS in about 500 innings of outfield time last season.
The Royals' infield defense is excellent as well, with three-time Gold Glove winner Eric Hosmer at first base, Gold Glover Alcides Escobar holding down shortstop and Gold Glove candidate Mike Moustakas at third. Omar Infante and Christian Colon could split time at second base.
Catcher Salvador Perez also has won three Gold Gloves, and while rival evaluators see little things in his defensive play that they'd love to see him clean up, he's greatly respected for his on-field presence and the way he works with pitchers.
2. Arizona Diamondbacks
Center fielder A.J. Pollock led NL center fielders in DRS in 2015, and first baseman Paul Goldschmidt won his second Gold Glove for his defensive play. Shortstop Nick Ahmed is like the Kevin Kiermaier of infielders -- casual fans aren't necessarily familiar with him, but scouts are, having seen him make a lot of athletic plays like this one.
The overall standing of the Diamondbacks' defense could swing on the choice the team makes at second base. Chris Owings could be the second baseman, giving the Diamondbacks a dominant defensive infield, or Arizona could look for more run production from the spot and opt for Aaron Hill's power. Catcher Welington Castillo joined the Diamondbacks last June, and Arizona really liked his work with the pitching staff.
3. Miami Marlins
Shortstop Adeiny Hechavarria is like a soccer player in terms of athleticism, physically inventive in how he makes plays like those shown here. Second baseman Dee Gordon surprised a lot of folks -- including the Dodgers, probably -- with his improvement, and he was rewarded with a Gold Glove. Martin Prado rated among the best third basemen in DRS last season, posting a plus-9.
The secret weapon in this defense might be Giancarlo Stanton, who is one of the biggest players in baseball but is a lot better defensively, in terms of how he moves and throws, than a lot of fans realize.
The Pirates' outfield is excellent, with Starling Marte, Andrew McCutchen and Gregory Polanco as their starting trio, and because of how they pitch inside and position their infielders effectively, the team's range issues at second, short and third tend to be mitigated. If there were a metric for team defense, for positioning, the Pirates would be MLB's leaders over the past five years.
Catchers Francisco Cervelli and Chris Stewart are an excellent tandem, with Stewart credited for getting a lot of low strikes and Cervelli ranking as MLB's No. 1 pitch-framer last season.
5. San Francisco Giants
The Giants' infield is as good overall as any in baseball, with Gold Glover Brandon Crawford at shortstop, the underrated Matt Duffy at third base, All-Star Joe Panik at second base and Brandon Belt at first. The perception among a lot of evaluators is that Buster Posey's work behind the plate continues to get better and better, and this is reflected in his high standing in Statcorner.com's pitch-framing rankings.
The Giants' decision to spend $31 million on Denard Span to be their center fielder surprised some rival executives, because they see him as a player coping with injuries and defensive regression. The questions about him are: Is that regression simply due to injury? And if he's now healthy, how good will he be?
Angel Pagan is expected to move to left field, with Hunter Pence in right field.
It's not clear when Devon Travis (shoulder surgery) will be back at second base for the Jays; until then, Ryan Goins, a good defender, may get the bulk of the playing time. Kevin Pillar, baseball's Spider-Man, will be in center field, and shortstop Troy Tulowitzki and third baseman Josh Donaldson will get a chance to play a full season together on the left side of the Toronto infield. Russell Martin is among baseball's best defensive catchers.
Look, having Kevin Kiermaier as the anchor of the team's defense is a little like having Mike Trout or Bryce Harper as your No. 3 hitter: The man is a monster with the glove. Last year, Kiermaier knocked Andrelton Simmons and Jason Heyward off the top of the defensive runs saved rankings, crushing the field -- and whether you believe in the precision of this number or not, the fact that he scored so highly in a metric that many evaluators cite these days says a lot about his play.
Leaders in DRS, 2015
Kevin Kiermaier: 42 DRS
Ender Inciarte: 29
Andrelton Simmons: 25
Starling Marte: 24
Jason Heyward: 22
Second baseman Logan Forsythe is coming off an excellent season for the Rays. Shortstop Brad Miller, acquired from the Mariners just after the 2015 season, should represent a defensive upgrade over Asdrubal Cabrera, and the Rays have good catching in Rene Rivera and Curt Casali.
Two years ago, the Indians were arguably MLB's worst defensive team, but their universe looks very different now that Francisco Lindor is their shortstop and second baseman Jason Kipnis is healthy. Catchers Yan Gomes and Roberto Perez are good defenders, and new first baseman Mike Napoli should represent a tremendous upgrade over Carlos Santana. Michael Brantley is an X factor coming off shoulder surgery; the Indians are cautiously optimistic that he'll be back sometime in the first couple months of the season. When healthy, he has been solid defensively, but without him, Cleveland will have to improvise. Lonnie Chisenhall, slated to be the team's right fielder, posted a top-5 DRS in right field in 2015 despite playing just 354 1/3 innings there.
The Braves targeted catcher Tyler Flowers partly because of how good he is at pitch-framing -- he was second in the majors in this metric (behind Cervelli) last season. They also added the aforementioned Inciarte as an outfielder, following his tremendous defensive season. Freddie Freeman is capable at first, right fielder Nick Markakis is now 32 but has won two Gold Gloves, and while Erick Aybar is not as good as Andrelton Simmons -- nobody is -- he's still solid.
The Orioles have the potential to be higher on this list, depending on the relative health of shortstop J.J. Hardy, center fielder Adam Jones and catcher Matt Wieters, as well as the composition of their corner outfield spots. Meanwhile, third baseman Manny Machado is one of the game's best defenders.
Best of the rest: The Los Angeles Angels have Simmons at shortstop and Trout in center field, and the coaching staff has liked what they've seen in young catcher Carlos Perez. That's a great spine for a defense. … The Boston Red Sox could be strong in the outfield and middle infield but have enormous questions at first and third base, with Hanley Ramirez and Pablo Sandoval, respectively, at those spots.
The Houston Astros could use a full season from George Springer and Carlos Gomez tracking down fly balls in their outfield. … The Oakland Athletics will presumably get more consistent play in their middle infield this season. … And finally, the Colorado Rockies have a Gold Glover at third base (Nolan Arenado) and a former Gold Glove winner at second base (DJ LeMahieu) but have questions at shortstop and first base.

Justin Upton, Rangers a good fit
If Justin Upton gets to the point when he seriously thinks about a one-year deal -- back in December, the reasons that might make sense were laid out here -- the Rangers may well be the best option.
Texas has an excellent lineup already, they inhabit a really good hitters' park, and Upton wouldn't go there expected to carry the offensive load himself. He could slot in among Prince Fielder, Adrian Beltre, Shin-Soo Choo, Rougned Odor and others and do some major damage there, which would give him an excellent chance to play in the postseason before hitting the market again next fall.
Imagine a Texas lineup that looked something like this:
1. CF Delino DeShields (bats right)
2. RF Shin-Soo Choo (left)
3. 3B Adrian Beltre (R)
4. DH Prince Fielder (L)
5. LF Justin Upton (R)
6. 1B Mitch Moreland (L)
7. C Robinson Chirinos (R)
8. SS Elvis Andrus (R)
9. 2B Rougned Odor (L)
Josh Hamilton could effectively become a fourth outfielder, rotating in and out of the lineup as needed, depending on injuries, matchups and which players need rest each day.

Notables
• Ken Davidoff writes about how the Chris Davis deal affects the Yoenis Cespedes bidding. Cespedes and the Mets are a perfect fit, writes Bob Klapisch.
This is worth repeating from yesterday's column: The Mets have made it apparent that they do not want to spend the money that would be required to sign Cespedes, but the pressure to do so is growing, as analysts and columnists reflect the desire of New York fans.
If I were in Mets GM Sandy Alderson's shoes, I wouldn't give Cespedes a megadeal now either; rather, I'd save the available money for the season and wait to see what needs develop. Their starting pitching is so strong and so deep that there is no reason for them to overreact or act rashly, and unless the Mets' payroll is going to increase significantly -- and that's the call of ownership, not Alderson -- then it's better to hold back that financial ammunition until the most serious roster problems are revealed by the first half of play.
Michael Conforto should help the offense, as will Neil Walker and Asdrubal Cabrera. Will the Mets' lineup be dynamic? No, but it doesn't have to be.
Remember, it appears that as many as six NL teams are either rebuilding or tanking, including a couple of NL East clubs, the Phillies and Braves.
• There are still some really good free agents available, including Howie Kendrick.
• The Orioles still have work to do, writes Peter Schmuck. Dan Szymborski looks at the Orioles' chances for success now that they've re-signed Davis.
• Mariners catcher Jesus Sucre suffered a broken leg. Seattle will go into spring training with Steve Clevenger, Chris Iannetta and Mike Zunino as their other catching options.
• Cubs president Theo Epstein says there are no indications the DH is coming to the NL anytime soon, and that the issue is above his pay grade.
• Cardinals owner Bill DeWitt Jr. gave his views of the hacking episode.

Moves, deals and decisions
1. Sarah Gelles was promoted by the Orioles.
2. The Jays added to their front office, hiring Mike Murov from the Red Sox.

NL East
• Nationals GM Mike Rizzo feels his roster is now balanced.
• Outfield prospect Nick Williams gives the Phillies some hope, writes Mike Sielski.

NL Central
• Jesse Rogers has some observations from the Cubs' convention.
• Derrick Goold writes about the Cardinals' age.
• A Cubs prospect seems ready to turn the corner.
• The Cubs' future is in the hands of business president Crane Kenney.

AL East
• Former big league reliever Alan Mills can relate to the jump that young Orioles pitcher Jason Garcia is trying to make.
• The Red Sox are rolling the outfield dice on Rusney Castillo and Jackie Bradley Jr. Speaking of Bradley Jr., he's poised to be the everyday center fielder.

AL West
• The talk of the Rangers moving to Dallas is more than just hot air.

Lastly
• Eric Davis is using his experience to help players.
• The St. Louis baseball writers' dinner was poignant.
And today will be better than yesterday.