Click into the post for a better view of the graphs
According to the charts, it would seem Matt Murton is hitting baseballs this season at about the same pace as his first year.
One other chart that might be of interest:
It should probably be noted that Murton started tinkering with his swing after the 2010 season in an attempt to increase his power output. He reportedly reverted to something closer to his year one swing this year. It should also be noted that the standard NPB baseball was introduced in 2011.
Below is video of four swings, one from each of his four seasons. All four swings resulted in home runs, but the pitches and locations are different, so it may not be the best footage to compare.