Buster Olney ranked his top 10 team defenses in his blog post Thursday, which got me thinking about bad defense. I checked Baseball-Reference.com for their list of worst individual fielding seasons and thought it would be fun to look at the bottom 10. Defensive metrics aren't as foolproof as some other numbers, so let's dig deeper into what may have caused these poor ratings. Plus, don't you want to read about the worst defender ever? Make a guess now ...

(Note: Baseball-Reference uses fielding runs below average, which can be drawn from two different sources depending on the year. Since 2002, the site uses defensive runs saved; prior to that, it uses total zone. A third defensive metric that I'll mention in the piece below is ultimate zone rating, available at FanGraphs. It's also interesting that all 10 seasons here occurred since 1990, which is a reflection of more data available to grade defense.)

10. Kirby Puckett, CF, 1993 Twins (minus-29 runs)

This one seems a little odd considering Puckett had won a Gold Glove the previous season. Puckett's defensive metrics don't match up to his reputation -- he won six Gold Gloves -- as Baseball-Reference grades him out as 14 runs below average for his career. By 1993, Puckett was 33 and had put on some weight; it's perhaps instructive that the Twins moved him from center field to right field after the All-Star break. Twenty-eight of those 29 runs below average came as a center fielder, where he made 2.50 plays per nine innings compared to the MLB average of 2.76. The Twins walked the fewest batters in the AL and were in the middle of the pack in strikeouts and home runs allowed but were 13th in hits allowed, so the team defense was pretty bad overall, with Puckett apparently playing a big role. (My recollection of Kirby, as well: He played a deep center field, which allowed him to make those famous leaping catches at the wall; he also may have played deeper as a way to play the high bounces off the Metrodome turf.)

9. Rickie Weeks, 2B, 2012 Brewers (minus-30)

Weeks has never had a good defensive reputation and in 2012 he started 152 games at second base and made just 4.08 plays per nine innings compared to the league-average range factor of 4.77. I'm not sure if he played through an injury or if they used quicksand for infield dirt that year at Miller Park, but in the past five years, the second-lowest range factor for a regular-season second baseman was 4.31 plays per nine innings -- by Weeks in 2011.

8. Nick Castellanos, 3B, 2014 Tigers (minus-30)

Castellanos' range factor was 2.10 per nine innings compared to the MLB average of 2.56, but of course he played on a staff that racked up a lot of strikeouts. Still, that's nearly one fewer play every two games. Baseball Info Solutions categorizes plays as good fielding plays and defensive misplays and Castellanos' total of GFP minus DM + errors ranked second worst among third basemen in 2014. As for his range, BIS graded him particularly weak going to his right. The hope for the Tigers is that Castellanos is young enough to improve, but he needs a lot of improvement just to become league average.

7. Gary Sheffield, 3B, 1993 Padres/Marlins (minus-31)

Nobody will dispute this rating. This was Sheffield's final season as a third baseman and he made 34 errors while fielding .899.

6. Michael Young, SS, 2005 Rangers (minus-32)

This one may be a bit surprising as Young was regarded as a solid shortstop and even won a Gold Glove in 2008. You know what the Rangers thought of that Gold Glove? They moved him to third base the following season. Anyway, Young had come up as a second baseman and moved to shortstop in 2004 and in 2005 he made 4.41 plays per nine innings versus the MLB average of 4.60 (his fielding percentage was about league average). Baseball Info Solutions tracked him with 30 good plays and 39 misplays and it's worth noting that ultimate zone rating had him at minus-23 runs and total zone at minus-31 runs. So all the metrics agreed that he just didn't have much range in this year. Young did seem to improve after that, perhaps with better positioning.

5. Ryan Braun, 3B, 2007 Brewers (minus-32)

This was Braun's rookie season when he came up as a third baseman and he was such a disaster there the Brewers moved him to left field in 2008. Braun fielded just .895, making 26 errors in 112 games, and made .57 fewer plays per nine innings than the average third baseman.

4. Chris Gomez, SS, 1997 Padres (minus-33)

I never thought of Gomez as a bad fielder, but I guess I never really gave all that much thought to Gomez in the first place. Gomez's range factor was actually higher than the MLB average, 4.63 to 4.58, and his fielding percentage was fine, so I'm not quite sure why he rates so poorly. The Padres were third-to-last in the majors in defensive efficiency (percentage of balls in play turned into outs), so a lot of Padres defenders ended up with poor ratings in 1997. The Padres made the playoffs with Gomez playing shortstop in 1996 and 1998, so they apparently didn't think he was awful there.

3. Dante Bichette, LF, 1999 Rockies (minus-34)

This one makes a lot of sense: An old outfielder trying to play in Coors Field. Bichette was fast enough to play a little center field early in his career, but by 1999 was 35 and lumbering. He had poor range -- 1.77 plays per nine innings compared to the 2.00 MLB average -- and also tossed in 13 errors. Even though Bichette hit 34 home runs and knocked in 133 runs, the Rockies traded him after the season.

2. Matt Kemp, CF, 2010 Dodgers (minus-37)

Much like Derek Jeter, there has been a lot of divisiveness over the years about Kemp's defense. Sandwiched around this all-time bad season are two Gold Glove honors in 2009 and 2011.

Let's look at his range factors per nine innings:

Year Kemp MLB

2009 2.53 2.60

2010 2.23 2.59

2011 2.32 2.55

In raw numbers, Kemp played nine fewer innings in 2010, but made 37 fewer putouts. Kemp also had just three assists in 2010 compared to 14 in 2009 and 11 in 2011. Did he deserve those Gold Glove Awards? Probably not. In 2009, he did make a high number of good fielding plays (48), according to Baseball Info Solutions, although that was countered by 33 misplays. Undoubtedly, voters remembered the spectacular plays, but there was nothing in the numbers that suggested Kemp had above-average range and he was making a large number of miscues at the same time. In 2010, his ratio of good fielding plays to misplays fell to 26-28, which combined with poor range gave him minus-37 defensive runs saved. UZR had Kemp at minus-26 runs that year, the worst total it has ever given a center fielder going back to 2002, so by all accounts Kemp was awful.

1. Adam Dunn, 1B/LF/RF, 2009 Nationals (minus-43)

I don't think anyone is going to defend Dunn's defense. He was a huge dude and while his outfield defense wasn't terrible in his first few years, he soon became huge and slow. In 2009 while playing for an awful Nationals team that lost 103 games, Dunn started 83 games in the outfield and 66 at first base. It's no surprise that he rated poorly in the outfield -- minus-20 runs -- but he also rated minus-23 runs at first base in just 540 innings. Was he really that bad? Well, he hadn't played the position much before that and isn't exactly quick to begin with, so it's easy to assume he combined a lack of range with a lack of experience. In left field, he made 1.80 plays per game while teammate Josh Willingham -- hardly known as a plus fielder himself -- made 2.17. Dunn recently confirmed his retirement and I'll miss a guy who had a unique career in major league history. But I probably won't miss his defense.