Before the season I looked at home run rate (per pitch) by pitch location. In that post I found that the highest home run rate was slightly up and in within the strike zone, a finding which has since been confirmed and expanded by Jonathan Hale. That post also presented some hitters who hit lots of home runs outside of that up and in region. Two examples I gave were Carlos Pena and Carlos Quentin. Here are the images I presented, with the average HR rate of all LHBs for Pena and RHBs for Quentin in gray and their 2007 and 2008 home runs plotted over that in red. Remember these images are from the catcher's perspective so Pena, a LHB, stands to the right of the strike zone and Quentin to the left of the zone.

Both hit most of their home runs down and away, and very few in the traditional power region up and in. They also happen to be at the top of this year's early HR leader board, Pena tied for the lead with nine and Quentin just one behind with eight. It was interesting for me to see the two of them at the top of the list after profiling their abnormal home run hitting patterns before the season, so I wanted to check the pitch locations of their home runs so far this year. I used the images from above, shrunk the 2007 and 2008 home run indicators a little and plotted the 2009 home runs with larger circles.

The home run locations are still fairly different from the average hitter and pretty close to the 2007 and 2008 locations. The centroid of Pena's 2007 and 2008 home runs was (-0.10,2.39) and of his 2009 home runs (-0.16,2.56). So his home runs so far have been even more outside than the last two years and slightly higher. Quentin's '07/'08 home run centroid was (0.18,2.33), and his '09 home run centroid is (0.03,2.26). So his home runs have moved in, but are even lower in the zone than the last two years. Both are still hitting more home runs in the outside half than in the inside half of the zone, which is very different than the average hitter. It is interesting that these two top home run hitters generate so much power in a location where most hitters have a near zero home run rate.

EDIT:In the comments Rich asked a great question about what type of pitches Quentin and Pena are hitting for home runs. Here is the breakdown of home run rate per pitch by pitch type for each of them and the over all league average.

+-------------------+-------------+-------------+-------------+
| HR rate per pitch |     Quentin |        Pena | Leag. Aver. |
+-------------------+-------------+-------------+-------------+
| Fastballs         |      0.0174 |      0.0163 |      0.0071 |
| Changeups         |      0.0132 |      0.0068 |      0.0075 |
| Sliders           |      0.0104 |      0.0180 |      0.0056 |
| Curveballs        |      0.0275 |      0.0089 |      0.0049 |
+-------------------+-------------+-------------+-------------+

Pena's per pitch rates are lower than Quentin's but his over all number of home runs is higher because he sees more pitches per plate appearance (4.0 versus 3.6). For almost every pitch type they hit more than league average, but the difference is very high for Pena with sliders and for Quentin with curves. So I graphed their home runs by pitch type.

It looks like sliders for Pena and curves for Quentin are really pulling their average location down and away. Their fastballs are a little bit more away and down than the average hitter, but I think what makes their home run locations particularly distinctive is the large amount of breaking pitches they hit for home runs which are down and away. From Hale's article it does not look like most hitters sliders and curves for home runs in these locations. Great question Rich.

EDIT 2: Rich made another great suggestion of looking at the locations of where all these home runs ended up. First Quentin:

Rich's take, which I agree with:

I was surprised how many home runs he's pulling given your findings. I think it shows how strong he is as the average hitter wouldn't be able to turn on those breaking balls on the outer half of the plate like Carlos.

Now Pena:

Pena is hitting lots to dead center. It would be interesting to combine the two data sets, and see how the location of the pitch corresponds to the location of the home run, like Max Marchi did here. Or look at how the location of home run corresponds to the pitch type.