Or does it?

No, your league isn’t likely to add UZR/150 or Total Zone as a category next season. But if you’re playing in an AL or NL only league – or even a mixed league – defense could play a huge impact on several players production.

Let’s start with an obvious example. Mike Napoli. The Angels catcher could be a great fantasy asset. He has a tremendous amount of power, hits in the middle of one of the better lineups in baseball, and probably wont destroy your batting average. There’s just one problem. He’s failed to reach 400 at bats during any season in the big leagues. He hasn’t bee the healthiest guy out there, but he did spend most of last season on the active roster. So why can’t he get into the lineup if he’s such a good hitter?

A quick look at Driveline Mechanics 2009 defensive runs above average shows us why. Napoli was just about the worst defensive catcher in the Major Leagues last season, costing his team almost 10 runs behind the plate, despite catching fewer than 100 games. While Joe Mathis isn’t exactly a stud by these metrics, he’s certainly better than Napoli, and Mike Scioscia considers him one of the better defenders in the league.

But that’s pretty obvious, right? Most fantasy players know this. Let’s look at a less obvious example.

I was listening to the Fantasy Baseball Roundtable Tuesday night, and they were discussing the Oakland A’s outfield situation. This is a huge deal in most formats – guys like Rajai Davis, Coco Crisp, and Michael Taylor could be major fantasy assets if given playing time, and are especially valuable in mixed leagues.

Totally aweseome outfielder.

One guy who isn’t exactly a fantasy stud is Ryan Sweeney. While Sweeney is a career .284 hitter – and hit over .290 last season – he hasn’t developed much power and isn’t going to steal many bases. You could do worse in AL only leagues, but we’d certainly rather see a guy like Coco Crisp – who could steal 20-30 bags – get the playing time. The question was, why is Ryan Sweeney getting 500 plate appearances? He hits for a solid average, but guys with sub-.400 career slugging percentages don’t usually start in corner outfield spots. What do they see in Ryan Sweeney?

One word. Defense. Last year, Ryan Sweeney was worth 24 runs defensively over the average player between CF and RF. That’s about equal to the offensive contributions of Raul Ibanez, Robinson Cano, or Ichiro Suzuki. He also has a bat right around league average. Now, if I told you that you could have Robinson Cano’s bat, and league average defense (that’s basically what Cano gives you, and I’m being kind) wouldn’t you take that? According to FanGraphs, Sweeney was a 4 win player last year in only part time play. Those guys are incredibly rare, and he was worth over $18 million dollars. Billy Beane isn’t going to give that guys job away to a scrub named after a brand of cereal.

This is where defense really matters in fantasy baseball. You’re average fantasy owner will look at the Oakland A’s outfield situation, see Ryan Sweeney’s mediocre numbers, and decide he wont keep his job going forward. But add in a 20+ UZR, and he goes from a 4th outfielder to a 4 win stud who is very unlikely to lose his job.

A couple more examples of this can be found in Michael Young and Johnny Peralta, who both had to move to 3B (a less scarce position) because of their poor defense. Or even Nyjer Morgan, who was able to gain consistent playing time because of his glove.

While this might not help you in too many situations (Derek Jeter isn’t going to lose his job to Ramiro Pena, no matter how bad his defense is) it’s just another piece of information that can help you when looking at position battles and bench players who may get a chance to play everyday. More useful in AL and NL only leagues, but can have an impact in any format, as the A’s outfield situation shows.

Over the next couple of months we are going to be doing a series of previews for all 30 MLB teams, highlighting one or two interesting themes going into 2010. We will also be including interviews with several bloggers and analysts. We don’t want to be excused of having an east coast bias, so we’ll start of with the AL West this week and into early January. Up first: The Oakland Athletics, and an interview with A’s blogger Nico Pemantle from Athletics Nation.

To lead off our team previews, were taking a look at the Oakland A’s, specifically a couple of young, highly touted pitchers who went in completely different directions in 2009. Way back in August I profiled several breakout pitchers for the 2010 season. Atop my list was A’s left hander Brett Anderson. Here’s what I said:

Brett Anderson is likely to be atop many breakout lists next season. That said, it will be worth it to over pay. Anderson’s ERA this season sits a 4.54, but looking at his skill set, we see a future ace. He has a healthy 7.34 K rate, a BB rate under 3, and a GB% approaching 50%. He truly has every skill you look for.

Anderson’s final numbers look even better. His ERA dropped to 4.06, as his K rate rose to 7.7 and his walk rate reached an incredibly low 2.31. In fact, over the last decade, among rookie pitchers with at least 175 IP, Anderson has the highest K/BB rate, the second fewest walks, and the second lowest BB rate. His GB% for the season was 50.9% and his xFIP was 3.61.

Anderson’s second half numbers will add a few bucks to his final price in most auctions, but I’m not going to complain. After the all star break, he went 6-4 with a 3.48 ERA, a 4.30 K/BB rate, and a FIP of 2.96. His K rate of 8.8 was a significant improvement over the 6.6 he posted in the first half. The only question mark here is his work load, but I’ll live with it. He’s going to be on a lot of my teams come 2009.

Fellow rookie Trevor Cahill came into 2009 as arguably the top prospect in the A’s system, even over Anderson, and like Anderson, started the season in the rotation. He may have been doomed from the start – he had less than 40 innings above A ball – but either way, the results weren’t pretty. His 4.63 ERA was bad. His 4.5 K rate, 1.25 K/BB rate, and 5.33 FIP were worse.

Of the two pitchers, I clearly like Anderson a lot better, for next season, and long term. Cahill’s value is limited to dynasty leagues, and deep AL only’s, but I’m not ready to completely give up yet, because he clearly wasn’t ready for the big leagues last season and his GB%, average control, and nasty low-minors K rates provide a good amount of hope. But his FIP says 2010 could be even worse. Rostering him is a risky move.

Answering our questions about Anderson, Cahill, and some more general questions is Nico Pemantle from Atheltics Nation:

FBP: First off, thank you for taking the time to answer a few questions for us. Easy question to start off. How do you see the Athletics finishing in 2010? Record?

Nico: As much as it pains me to say it, and as good as I think/hope the A’s will become 2011, I would have to predict a last place finish for Oakland in 2010. As the roster currently stands, Kurt Suzuki looks like he could be the team’s HR leader with around 15, there isn’t a single hitter I would really want batting #3 or #4, and 3B is still a black hole with SS in the uncertain hands of Cliff Pennington.

If and when Michael Taylor, Chris Carter, and Adrian Cardenas arrive, it’s a whole different story. But the 2010 team looks like a scrappy bunch that will alternate winning and losing games 3-2. I see this team, as currently constituted, going 79-83, with a strong second half as the offense improves upon the arrival of some good young hitting talent.

FBP: The main focus of my 2010 Athletics preview is Brett Anderson, who I think will emerge as an ace in 2010. You simply don’t see many 22 year olds who strikeout that many people, keeping the walks in check and inducing groundballs, and his second half performance showed significant across the board growth. What would you project Anderson’s ’10 line to be, and what do you think he still needs to work on?

Brett Anderson, ace?

Nico: I agree about how good Anderson is. Add to your praise the fact that he is unusually poised and mature — both unflappable and shrewd about how to work big league hitters. Assuming good health, and factoring in that he plays half his game in a very good pitcher’s park, Anderson is fully capable of putting up a line of something like 17-10, 3.30 ERA. Subtract some wins if the offense refuses to score any runs behind him, but the bullpen should be one of the best in baseball.

FBP: One concern I have about Anderson is the workload. In 2008, he threw 105 innings, compared to 175 last year. That jump raises somewhat of a red flag. How do you think he’ll handle it going forward?

Nico: My concern about Anderson is not so much the innings workload, but the fact that his natural physique is not the ideal athlete’s build. Now he’s been working hard, and apparently very successfully, with Bob Alejo (A’s Strength & Conditioning coach), but we’ve already seen Anderson miss a little time due a “stiff back” and a recurring blister. Anderson still, to me, has the potential to become another Justin Duchscherer — an ace when he’s out there, but often shelved due to this or that.

I’m less worried about the IP because Anderson, by nature, economizes his pitches, and not all innings are alike. The A’s kept him around 100 pitches every start and he just got a lot of innings out of 100 pitches because he throws quality strikes.

FBP: Going into last season, most rankings actually had Trevor Cahill, not Anderson, as the A’s top pitching prospect. He struggled quite a bit in 2009, but do you think he can correct that next year? Where did his strikeouts go? Should he start the year in the big league rotation, or maybe move back down to the upper minors, where he has very little experience?

Nico: “Cahill going forward” is the subject of much controversy on AN, because his peripherals were even worse than his basic stats, and some feel he was not only rushed unnecessarily but possibly damaged and/or exposed as not that good.

I’m a bit more optimistic on Cahill, because throughout the course of the season his changeup improved greatly and in August and September he developed a slider that he hung far less than he had hung the curve/knuckle-curve in April-July.

He’s also only 21, having already gotten big league experience and learned some key adjustments with his stuff. I don’t see any reason Cahill can’t be a very good pitcher in the future — but I imagine his breakthrough season will be 2011, not 2010, as he is very much a work-in-progress.

Specifically, he lacks the most element that is most essential for a major league pitcher: fastball command. Whenever Cahill develops the ability to throw his fastball consistently where he wants to, he will take off. That could happen in April, 2010 or never. My guess is it will happen somewhere in between, such as around the 2010 ASB.

FBP: How do you see the A’s outfield situation playing out with Taylor, Davis, Crisp, etc.? Do you think Taylor will see any substantial playing time in 2010?

Nico: Yes, but not in April. Partly because he’s had fairly little time in AAA and partly because it would be foolish to allow a slugger to become a “Super 2″ in arbitration (which tends to reward sluggers), Taylor should not make the team out of Spring Training. But if he tears it up in AAA, I don’t see why he can’t be called up in May or June, for keeps.

Until then, barring a trade I’d expect to see an April OF lineup of primarily Crisp, Davis, and Sweeney, which could be one of the best defensive OFs in baseball — as well as one of the most pathetic ones in the HR column.

FBP: Andrew Bailey was fantastic in 2009, but past him, who do you see at the top of the bullpen depth chart going into next season? When is Joey Devine expected back?

Nico: Partly because Devine is coming back from injury (he’s expected back for Spring Training, though this puts him at the top end of the recovery scale), I think Bailey will be the team’s closer and Devine the set-up man. Behind them you have Michael Wuertz and Brad Ziegler, and from the left side you can choose from Craig Breslow, Jerry Blevins, and Brad Kilby. That’s a pretty deep and generally fantastic bullpen.

FBP: We all know the A’s farm system is stacked, but for dynasty league owners, can you give us maybe one or two under the radar names?

Nico:Anthony Capra doesn’t get a lot of press but looks like he could be a very good pitching prospect. Rashun Dixon is raw but is also very young (18) and full of tools. Grant Desme strikes out a ton but has made recent strides and just tore up the AFL last month.

FBP: What Athletic do you think is most likely to exceed expectations in 2010? Most likely to “bust?”

Nico: Daric Barton is a “breakout candidate” for 2010. He failed when he was very young and immature but while he doesn’t have a lot of power he has a chance to be a “Scott Hatteberg-type” player: Something like a line of .290/.370/.430, with very good defense, is not out of the question for Barton.

On the flip side, I just don’t see Pennington hitting in the big leagues over a full season. I’d guess he’ll have AVG and OBP closer to .230/.300 with very little power — I think a .650 OPS is perfectly possible, in which case his defense will need to be pretty spectacular to make up for his hitting.