I was in the middle of writing this post when I found out the sad news about Harmon Killebrew. I stopped and pondered whether it was appropriate to keep on. Many people have noted how the graceful tone of Harmon's statement about ceasing cancer treatment has been uplifting to them. On a day when I have something encouraging to say, I figured I should keep on saying it.

As we near the one-quarter mark of the season, I think we can start drawing conclusions about some things. Here's one where my eyes and the metrics are in total agreement.

Denard Span has improved significantly in center field.

Last year, there were complaints aplenty about Span's play in center field -- that he wasn't nearly as good in the field as he'd been as a left fielder in 2009 and a right fielder in 2008.

The complaints were accurate based on the metric Ultimate Zone Rating, which takes into account range, errors and runs prevented. Here's a more detailed explanation.

Adjusted for 150 games, Span's UZR as a right fielder in 2008 was 15.8. As a left fielder in 2009, it was 17.6.

As a center fielder last season, it was 6.4, sixth best among center fielders.

This season, using UZR, he is the best.

UZR is a "plus/minus statistic." In this case, zero is considered average.

This year, Span's UZR is 8.5, which plays out to a UZR/150 of 37.7 if his level of defensive play continues. UZR is a cumulative statistic -- like home runs or errors -- as opposed to being in the average/slugging percentage/ERA universe.

Only one other regular center fielder this season has a UZR above 4 -- and that would be this guy, who some of you may remember.

As much grief as Span took for his defense last season, his UZR was above average. It suffered in the public eye, I think, because he has been compared to Carlos Gomez, who has fabulous range but didn't always know what to do with the ball after catching it, and Torii Hunter, whose UZR numbers during his Twins years don't add up to the hype. (You can decide whether that's the fault of the statistic or the fault of our perception.)

The Twins absolutely need Span to be very good in center field because he is surrounded in the outfield by defensive liabilities. Jason Kubel's career UZR/150 is minus-17.8, even though he's at 0.4 (barely above average) for this season. Michael Cuddyer's outfielder career UZR/150 is minus-7.4, including minus-12.9 in 2009, minus-20.4 in 2010 and minus-22.5 so far this season. Delmon Young's UZR/150 last season was minus-11.2 and his career figure is minus-11.3.

The Twins made a decision to go with lesser corner defense in return for the offense that Kubel, Cuddyer and Young were supposed to generate. So far, one has been worthy, one has flopped and one is just coming off the disabled list. The fact that Young and Cuddyer each have good arms does not hide the fact that they are below-average outfielders.

Back to Span: He is clearly getting a better jump on the ball than he did last season and has taken better charge of the outfield. There were times last season when he wasn't as assertive as a center fielder needs to be, whether it was calling off teammates or appearing to get tentative as he neared the ball. His arm isn't as strong as those of the other Twins outfielders, but his range much more than compensates for that. Also, Span's offensive numbers are rebounding somewhat from what they were in 2010.

If the Twins were doing well right now, I'm sure more attention would be paid to Span's defensive contributions. So it makes sense to point them out as a bright spot amid the season's travails.